have used Freak kits before,
but just got my switch kit from stiffi a few weeks ago for my G7 Fly.
Gotta say stiffi are quality, and light, i mean paper weight..
Look down the inside of the barrel, and its like glass.
I used some old crappy paint and had a few barrel breaks, just shoot a few shots through them to clear it out with no problems.
Even shoots straight without the barrel on(just using the sizing breach).
If u have a few guns, then just use the 1 barrel and purchase the different breaches.