I am currently running it in a large scale railworld with about a dozen people.
Energy doesnt really scale so there really should be another way to increase the cost, I can't think of a way without another mod that adds currency. We currently have OARC which drops coins from biters, coins are then given value by the price of advanced gear in the item shop. You could add support for commonly used currency like "coin" and charge an overhead for it. Adding your own coin drops may or may not be outside the scope of this mod, but I like this idea because I'm a big fan of OARC and we already have a working economy based on coins :]
The other thing is, I am thinking of ways to automate trade, and I think I am getting somewhere. It would require disabling the shared chest in its current form though and perhaps using a warehouse or something that could easily be unloaded by a vehicle like a train or cargo ship. Then calculate the trade "completion" based on the number of items in the specified warehouse. I will let you know if I get any closer with specifics- I might mock up some code or try and do it myself with a pull request.
Speaking of requests. Would you be able to make a tab that saves all transaction history? It would be very cool to have data saved (which could later be exported, analyzed, or used in game)
Those are my current thoughts. 1.2.2 caused a desync earlier but was mostly stable. There is also a crash with Task List by Raiguard, possibly due to the shared shortcut (ctrl + T). You can try to replicate by having both mods in and pressing the shortcut a couple of times. Will do some more testing as you roll things out.