I have a Sirrus Elite 2004. I agree, the ride is very tight and responsive. I got Cane Creek bar-ends with it and I love the setup.

One point that also made me go for the Sirrus was the headset - the angle is adjustable, so you can get it the right height and angle that suits you.

I upgraded to the carbon seatpost that comes with the comp model - I have to admit I found the suspension seatpost a PITA.

I reckon you'll be fine with those gears - I can't imagine many hills on road/path that you wouldn't be able to handle with that bike. If you have had a chance to test ride, then check it out if you're not sure.

Sorry, I can't compare with the Marin. All I have to say is that I love my Sirrus!