It's not so much that you will be faster with the expensive kits or how much money you dump in it. Shoot I borrowed my friends 190 dollar ready to run brushed Kyosho db and ran great! The way I see it the extra money paid for will kick in the long run. The rod ends won't wear out as fast, the ball ends are much better metal, the arms don't twist, durability is what I was after. The losi scb is what 200? Then you need the tlr kit, another what 130? Yea not many shops carry them, but everything can be had with a click away.
Anything can be made to go fast and be just as reliable, just boils down to how much money and time you want to spend in it.
Want the rb5wc just can't get around the looks of it and how tiny they are.