low maintenance
Single pivot designs have only one set of bushings to maintain. For example, the Santa Cruz Heckler, a single pivot design has quite a reputation for being low maintenance. In contrast, the Specialized FSR has a four bar linkage and seem to need much more maintenance. I want to spend as much time as possible riding so low maintenance is pretty high on my list of "nice to haves". Although I initially was considering a FSR, this consideration has steered me into getting a SC Heckler instead.
frame durability
The Santa Cruz Heckler is available in Heckler and Heckler superlight (SL) models. The superlight is basically a standard Heckler with as much frame shaved off as possible. While the lighter frame is appealling, the 180lb rider weight limit suggests to me that the bike is significantly weaken in the process. Sifting through the use groups, I find the Heckler's achilles heel. The dropout hanger is not replaceable. One rider broke his hanger after three rides, a $250 repair.
The Aeon Isis is a single pivot design similar to the Heckler geometry however the tube design is quite different. It is a newcomer to the market, a frame that doesn't have the track history of the Heckler. However, users have been giving this frame rave reviews in mtbr.com. It does have a replaceable dropout and a superlight version of the frame is actually stronger than the standard frame. I've send a few emails to ask questions and the replies were prompt and courteous. Some more checking reveals that the frame has a lifetime warrantee and is built by Ellsworth, a respectable frame builder. Looks like I have a contender.
minimal bobbing, when pedalling
Full suspension bikes suffer from bobbing when pedalling. This is caused from the pedalling force compressing the suspension during riding. Some frame designs bob less than others. The Heckler isn't suppose to bob much. User reviews and in the May 2000 edition of Bike indicate that is Isis doesn't bob much during riding either. Unfortunately, I can't test any of the bikes so this is a leap of faith.
good user reviews
Bikers tend to really love (or hate) their rides. Mtbr has alot of reviews on more frames and components than I ever imagined existed. I don't have the experience to pick the frame and components for myself so I'm going to rely heavily on the mtbr reviews. Based on the mtbr feedback, looks like the Isis is a winner.
reasonable price
Aeon Isis ( frame only) is listed at $1095, the SL version is $1395. Certainly not cheap, but I'm worth it.