The guy from Hi-9 told me that when Yukon was designing the Grizzly they contacted Hi-9 and asked them what they didn't like about the Detroit and made some design changes because of it. In addition, he tells me that Grizzly is much better about tech support and replacement parts.
If I do an ARB, I may go with a Co2 air supply rather than a compressor. I've talked with guys who have run off of their Co2 tank and have used paintball canisters as backup. On the other hand, I like the idea of the Grizzly.