Hmm, Well, If your sure that full suspension is what you "know" you'll want and can afford it, buy it. I ride hardtails because I like the feel of a rigid rear end. I feel that I have more control of the bike.

One of my riding buddies has pretty much given me his trek liquid, it's a sweet ride, but sits in my garage most of the time.

Generally the Dually will be a little more heavy, and have more maintenance.

***It's realy boils down to what you like. Just try and ride both, don't buy in a hurry, or being pressured.

**** I would get the best bike I could afford from the get go. If you like the sport, you'll wish you had splurged on the high-end bike. If you decide later on riding is not for you, we'll thats part of life. Atleast you gave it your best, and you'll have a nice bike to putt-arround on.

Buying a low-end bike will cost you more in the end, because you'll want to up-grade later.

Hardtail vs. dual suspension is what I would be most concerned with.