Hi!
Pervolo is a great team! Special thanks to Denis Severin for quick responses and desire to help in solving problems in best way. Making the impossible things (for the conclusion of other developers :)). High-quality and fast implementation of desired add-ons. The price tag is quite nice, but in dollars (for those earning in rubles - this is not very conveniently). On the other hand, responsiveness and beautiful complex tasks must be paid in world currency.