I have just finished painting HATSs Russian Tank Riders and putting them on one of many Russian Tank and Self Propelled Guns I have. I find the SU122, SU152 adn SU 80s are very good for this purpose as they have good flat surfaces to put the troops on.
The figures also fit well in lorries/trucks such as the American 6 x 6 truck which was supplied in vast numbers to the Russia. Airfix used to make this kit and Hasegawa have made it for many years.Lesser known perhaaps is the Russians also used American Lee and Sherman tanks and British Valentines and Churchills under "Lease Lend" policies. I have yet to try to put Russian tanks rider on any of these, but that is my next project.
I worried about what glue to use to fix the tank riders on tanks but found that the best Superglues ae not very effective and ordinary plasic glue I use for the model tanks is absolutely great.
As to the future, I wonder if HAT would consider making sets of Japanese, Australian, Afrika Korp, 8th Army and US Marines tank riders.