First of all, THANKS FOR THE AWESOME ADVICE!
I want thinking about the challenger because it has a much faster cruise speed and basically just liked what I saw on their sites.
Couple of links that you may like! I would DEFINATELY go with the Rotaz 582 engine.
http://www.challenger.ca/twins_landlubbers.html
http://www.challenger.ca/twins_headstart.html
http://www.challenger.ca/twins_difference.html
http://www.challenger.ca/582_approved.html

Another that I am considering:
http://www.ultralightnews.ca/lilbuzzard/buzzardspecs.htm

Looks good to me. But then, I haven’t been on the ultra light scene for some years now. And around here, I’ve been known as the guy who’ll try a PT-6 chained to a sheet of plywood. The developments in ultralights over the past years are amazing. Just do all your homework before you buy. TALK TO OWNERS!! Not just the guy selling them. There's plenty of ultralight boards with lots to say. Join them now.
Bottom line:
It’s your preference. Just don’t forget the BRS. IT IS A MUST HAVE ITEM.
As for the 582. Great motor. I’ve flown some kits with them as PP, and never had an issue. I’m not sure of your size/weight, but I can tell you that I’ve flown fixed wing aircraft from empty 767s, P-51s, Pitts-S2Bs, Lears, 675 Caravans right down to our J-3 and that old QS-MX. Never, as in NEVER, have I ever though that I had too much power available. Now the times I wished I had more…….

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1980 300D - Veggie Burner !