cadd,
i don't mean to throw a spanner in your works, especially if you've already settled on a bike. but if you're still in the market let me share you with you what i went through.
i'm 5'8", 150# so i'm not to far from your size (though the bikes we feel comfortable on can be far from the same!) and recently bought my first bike in 15 years -- my last bike was a bmx bike when i was in elementary school!
i live in san francisco in the very hilly parts and wanted something to ride around for fun and possibly to commute with downtown. i originally wanted a mountain bike because 80% of the bikes at the LBS' are mountain bikes and that was very similar in riding style to bmx bikes. however i rode my friends track bike -- single speed, no brakes other than your leg muscles -- and was totally blown away by how much easier to pedal up hills and on pavement compared to the mountain bikes i had been trying (treks, specialized, marin and giant around the $600 range). i loved it! but he was scared to ride off ANYTHING higher than 1" and i like doing minor hucks with my bike.
wouldn't it be great if i could get that feeling of ease of acceleration and gliding along with some minor ability to take in on dir and be able to bunny hop curbs higher than 3"'s? enter my current bike:
redline cyclocross conquest.
it's alumnium, light, rigid EVERYTHING, entry-level parts (sora, vueltra and other "small-name" parts), but it has clearance and 35C knobbies and it's a blast! it does everything i want: hop curbs, ride small dirt trails, take the occasional root/rock, blast downtown and climb back up 20%+ grades; it feels nimble and i even like the yellow color. msrp is $799 but i negotiated 200 off the price because i was ready to walk out the store and apparently this isn't such a hot seller so the owner was willing to talk down the price to get it off his floor.
be aware if you try cyclocross bikes they tend to run larger than road bikes and they don't need as much stand-over height as mtn bikes. but to me they seem the perfect "city" bike with their mix of ruggedness (compared to strict road bikes) and their aggressive road handling (compared to the mtn bikes i tried in our price range). find the right fit and the drop handlebars are wonderful! i followed the rivendell recommendations and have the handlebars level with my seat post and my back hasn't hurt yet; i only have ridden about 30-45 minutes around town however and that includes a lot of changing position when at stop signs or if i have to get out of the saddle when climbing steep hills.
hope this helps! either way you go i'm sure you're going to love your bike IF it fits right!!
bt