I use the train engineer with LGB and Bachmann engines Plus the added extras such as thier accessoires for point control and loop settings Iff ypu are going to runn DCC make sure all of the controller boards are the same for each loco[:)]
I use stuff from everyone, all straight DC powered by an LGB pack with a Aristo Basic Train Engineer, all work just fine.
That caviet of only using the proprieters power supply is pure hooey! They use that only to get you to buy their stuff exclusively, if their is a problem I’ve never heard of service being refused becasue they were using someone elses power pack. Where you get into this issue is after modifications to convert to multi-train DCC, battery power and R/C, thats when you get intomodifying a stock setup that could void the warrentees, but even then most mfrs are good about customer service.