My buddy and I have purchased and flown about 6 different Yank kits. All I can say is that the kits rock! We're real fans of the flexible phenolic tubing. I'm really glad that Barry over at Loc Precision (new owner of Yank rocket line) decided to keep making the kits with flexible phenolic.
We have the Yank IRIS in both the 2" and the 4" kits. The 2" has flown many flights on G80s and can really take a beating for those times when bad things happen (motor ejection failure etc.). The 4" IRIS was used for my buddy's Level 1 cert during LDRS this past summer. He used a Pro38 I212 Smokey Sam for the flight. Absolutely beautiful flight.
I used a 3" Yank Sandhawk on an Aerotech H112 for my Level 1 cert and a 4" Yank IQSY on a Pro38 J285 for my Level 2 cert.