Heya. The Hi-Temp stuff does not work quite as long as the Opt polishes; it's in between Menzerna and Opt for working time I would say. Via rotary a lot of guys, including me, add some Opt Polish to EC to improve it's working time and make it a little less gummy, by PC you don't need that.
I've used almost all the hi temp compounds, EC leveler, HC leveler (aka 357 magnum), Medium Cut and Smooth Cut (aka light cut), so the only one they have that I haven't used (I think) is the "Heavy Compound". They are all similar in that they are very creamy and smooth, they spread well, work reasonably long and cut well. That said, I prefer EC/HC because they leave a very smooth finish given the amount of cut they have. Medium Cut I do not like very much; I can see no reason not to use HC instead of it. HC has more cut and leaves a better finish. I always get "Intensive Polish-esque" micromarring from Medium Cut, and the cut isn't as good as HC.
Smooth/Light cut is good, the cut level is actually surprisingly good for a "finishing" polish, it's probably closer to IP in cut than FPII - however the finish reflects that. On hard paints it will finish very nice, however on soft paints it will leave marring.
When it comes time to purchase them again I will be ordering 1 gallon of EC and HC, and 32oz of smooth. I will be skipping medium. I will order smooth just because it has it's uses in some cases, however on 90% of the cars I do now I use either EC or HC, then finish with 106ff. EC/HC are really the standouts. HC is my favorite compound, period.