I was thinking to get the same thingz
M.troniks is a UK based company
the Viper RV Max seems to have weak mosfet(some of the guyz complaint it overheated and burn out), but it's water prove. if you run in a cold and wet weather. it is definitely the esc to go for.
MOPED V16R (Plus)
MOPED V16R (Pro)
both have listed with extemly well spec mosfet on board. even better spec than novak's GTX, if that's their ture spec. hongkong or chinese based company. from the design I see, they should really have some well spec mosfet, otherwise the case they are in would overheated at no time without the heatsinks. add a heatsink, they should be quite good and cheap.