Welcome back! Here's my $0.02. I would skip the Jeep. First off it's a Jeep. Second, it's pretty small. I know the X5 is not exactly a big cargo carrier but from looking at the current Jeeps, they are pretty cramped. Third, as far as it's performance, it sounds like a badass vehicle but FWIW, C&D rated the Trailblazer SS a better performer. I haven't driven the SS version of the Trailblazer but the regular version is typically terrible. I think you'd ultimately get bored of and regret getting the Jeep. Also, I don't think you can mount a hitch on the Jeep given the location of the fat twin exhaust.
I see that you're looking at 4.6is's and that's very cool as I'd love one but maybe you should consider leasing an '06 4.4 instead. You mentioned leasing and I know that BMWFS has some good stuff for X5's right now. When I went in last weekend to see about leasing a 330, the sales manager asked me about 3 times whether I was sure I didn't want an X5 because the deals were good. You'd get to lease, you'd get a brand new X5, all your maintenance is included, and be right in or below your price range. Your towing needs would be met too.