My first complaint is the grammatical set up of the post.
A: I need more specifics. I don't know what you mean. I will look over it again.
Secondly, assuming this item is mass produced it would quickly become known as defected or regarded as cursed when similar instances of theft began to take place among the holders of this brand of bag (assuming that the exquisite quality is a constant that consumers can identify the craftsman by).
A: Not true. Sid doesn't mass produce them. The creation of them is highly dangerous. There are probably a few hundred in the world, not a few thousand per city. Bags of holding are still expensive, and only travelers tend to have use for them, so unless all the adventurers of the world are getting together to discuss containers...
And if they spot it as cursed, it's just another bag of devouring. Not linked to Sid at all. A good adventurer will disenchant the bag and be on his way. It's just another cursed item. They exist.
Also, other than good craftmanship, there is nothing to distinguish Sid's bags from any other. If somebody did an in depth magical analysis, they could find a few call signs, but it is very rare to look that hard. Sid might not even sell many of them, preferring to leave them for people to find.
And last, rogues (at least in my games )target PC's just like anybody else. It isn't that far fetched to have something stolen unless special precautions were taken.
Next, Sid, if I presented this story to my party and omitted the bits about him stealing they would still instantly know, and moreover stage an assault on him to steal his bag.
I wholeheartedly disagree. Sid reads as a very wealthy trader who is on the non-lawful side. Given his frequent travel, it would literally be impossible to pin down a source of wealth, even if he was on the up and up. PC's might assume that he wasn't buying all of his merchandise, or maybe that he was running a shady bussines on the side, but I think it would be a stretch for them to assume that he was reaching through bags of holding and taking people's possesions.
As for assaulting Sid, good luck. As a powerful trader, Sid is an asset to everybody who is interested in rare things, and his contacts and allies span the world. That aside, the PC's would have to track him down first. He doesn't exactly hold still. Even if they find him, you have to assume that the PC's aren't the only brigands that Sid has ever handled. He wasn't rumored to have a philosopher's stone because he has a large inventory, and he does take precautions.
Sid shouldn't be presented alongside the bags of holding. They should be separate stories, not linked at all.
I don't see why people don't reach through there bags into his chest, if it is a two way street it seems like the first thing I would do.
There isn't anyting to reach into. It's just an extra-dimensional space that Sid also has access to. The evidence of that connection is MAGICAL, not physical. Imagine a room. In this room are two magical portals that only open up when somebody is reaching through. How would one person know that the second portal existed unless they were specifically looking for it.
Besides, you can only reach outside the chest...into what? Thin air? He doesn't put his own stuff into the chest. There is nothing to take.
I know that if my party just spent X days/weeks/months questing down a distinctly important piece of gear just to have it stolen by this guy they would think I set it up just to keep this item just out of their reach.
I should add this to my list of DM tricks to keep overpowered items out of PC hands. The point is, that as the DM, it's your call as to what gets stolen. If you don't want the PC's to lose their favorite stuff, then don't let it happen.
Besides, it is usually in Sid's best interest not to take something that will be noticed.
I really don't think that this scenario is that far fetched. If you have any more questions or commments, please let me hear them.
I think it is a useful item - in my mind related to the Bag of Other People's Stuff though a much more in depth post. I'll admit that Sid's name is used perhaps a little too often in the Sid section - 'he' would suffice - though this is not really that important.
Don't remove Sid from the post, just abbreviate his section and add a link to his sub.
Once the idea "leaked" to other mages, the idea of bags of holding that could be accessed other ways would become a subject of aggressive magical research, so there might be a number of other mages trying to investigate the properties of Sid's bags.
"I checked to see if it tied in to the extradimensional creature known as 'the Devourer', but came up blank. Nonetheless, there is something odd about those bags," said the magus... Go to Comment
So let me get this straight, This guy basically steals from his own customers using his special bags of holdings? Cool! It would be a fantastic plot hook to have the pcs purchase a bag and loose an item! cruel plot twist.
The bags could also have some unusual uses if the PCs find out. They could be used as doorways from one place to the next, a la teleport gate, allowing for some hillarious gateways:
"We're surrounded, we'll never get out of this one!, Everybody: Jump in the bag!"
or, if the chest is opened at the bottom of a lake, the bag could be used as a makeshift waterhose(ok, maybe not sid's own, but the idea of a two entrance bag does allow for that.)
oooh, the mischief that can be caused by this item! probably not a good thing to give to the PCs, then, but can lead to all sorts of trouble! Go to Comment
...among the items identified was a dolphin-shaped bathtub of marble and porcelain, a winged-back, high-chair of teak and velvet studded with fire opals, the gear-thing contraption from the dungeon-laboratory of Dr. Bezemot, the oil portrait of the rubicund Madame Orundilde Tarwygg, and a strange item known only as the Last Candle.