Smaller turbines mean even thighter manufacturing tolerances, so by definition not directly lower costs or price (like would be expected).
Personally I see a smaller turbine for jets only as a temporarily phenomenon, for modelers who wish to retrofit their D/F planes to turbines. I believe only few manufacturers see a lot of business opportunities in this gap of the market, the majority wants a turbine in the 10 kgrs (22 lbs) thrust class, and are only held back to even more powerfull/bigger ones because of the additional price.
Setting your turbine to lower output as suggested seems to me an excellent compromise, if your model accepts this size and weight. This is what I also advise any customer who wants JetCats, use a P120 even at lower thrust if you at first wanted a P80. You can use it later on in larger jets, and the P120 is seen as the best all-round turbine in their range at the moment, with the same very short delivery times now as the P80 as well.

Nicolas.