Those varieties are hardy here - that is why Reinder's markets them here.
I have heard more than a few guys on here say that slice overseeding with a majority KBG will not achieve very good results as germination takes so long and the seedlings are more apt to get choked right out by the existing stand of turfgrass. I need something that will emerge and be vigorous. I do agree with your rye assessment and I always mix in 20% rye or so.
7x14 Stealth SE Enclosed with 48" side ramp
08 Toro Z400 48" deck, 21HP Kaw with EZ Vac twin bag
09 Exmark Turf Tracer HP 36"
21" Toro SR4 Super Recycler
Stihl KM90 Kombi w/ straight shaft trimmer & tiller heads
Husqvarna 125B Blower
Turfco XT5 Aerator
Turfco LS-22 Overseeder
I can do all things through Him who gives me strength.