Hi Journey. The only thing that I know of between the 10lb models (CocoaTown or Santha) and the 40+ lb models is the Santha 20. If you're just looking at another smaller machine, there's also the Premiere Wonder Grinder, but it's smaller. I use it for small test batches. Others somehow use it for 8 lbs or more, but the chocolate has spilled through the center shaft every time I've gone over 4 or 5 lbs.
Regarding the belts, I'm surprised yours last 5 months! When I used the provided belts in either a CocoaTown or a Santha, they always broke within a month. The last one (on my Santha 40) broke after 3 batches. Basically, the provided belts are terrible. I believe it was Brad Churchill who first made the suggestion on this and the Chocolate Alchemy forum to replace the original belts with a PowerTwist fiberglass link belt. I've done that on all of my machines and have never had a belt break or need adjusting. I believe the smaller machines use 3/8" belts, while the larger machines use 5/8".
Regarding the Premier Grinder, are you referring to the 1.5 or 2 liter (tilting) model? I just did a 5 lb. test batch on the 2 liter model and it worked like a champ. It certainly could handle more and I'll find out how much in the next few days.
I have the smaller model.
There is a US distributor for the Santhas (in the San Francisco area). They offer the same price as on the Santha web site but their prices include shipping. Also, parts are available through them - not from India - and they offer technical support on the phone.
The belt upgrade that Ben mentions is a good idea and not that expensive to implement. LMK and I can put you in touch.