I "personally" do not think it will be very beneficial...the internal baffle is only 1 inch wide in the C6... Only 1.5 inches in the C8 so even the C8 can not take full advantage of a 2 inch diagonal...BUT the gain with the C8 is worth the price
BIGGER IS BETTER! You get roughly 50% more light with the C8. So what's an inch and a half? It's 38mm. Even among 2" eyepiece there are not many that have a field stop larger than 38mm. If you have a collection of 2" EPs go for it, but I wouldn't start one for a C6.
Personally, I was shocked when I inventoried my EP collection and found I had about about $5Ks worth. When I started culling and making those hard choices I found I kept the better 1.25"s and let the 2"s go. I still have cull some more....
3 Radian 4.7 Meade UWA 6 Radian 6.4 Meade SP (Japan) 6.7 Meade UWA 7.5 Ultima 8 Radian 9 Nagler type 6 10.5 TV Plössl 13 TV Plössl 13 Nagler type 6 14 Radian 15 Parks G.S. 5 16 Meade SWA 17 TV Plössl 18 Radian 20 TV Plössl 20 Meade S5000 24 Panoptic 26 Vixen Silvertop 26 Meade S5000 28 Meade SWA 32 TV Plössl 32 Meade S5000 40 TV Plössl 40 Optilux 40 Meade S5000 50 Optilux 55 TV Plössl