ORIGINAL: taildraggerdave

It is the last radio you will ever need. I race 1/5 scale road cars as well and if you go to any race, you will see 99% of the drivers using the 3PK. It even has an ABS setting that you can play with that will pulsate your brakes so they don't lock up. It has everything you will ever need. And, it really isn't that bad to program and understand.
Your 2 existing receivers will work as long as you stick with the normal spektrum and not the HRS spektrum unit. You will need to rebind the 2 receivers to your new 3PK/Spektrum transmitter and they will only respond to that Tx until you rebind them to something else.
Good luck, have fun.