I own the Mariavia Spider with a Downriver Equipment frame.
It's a two person boat if you want to go on overnighters. For day trips, taking three is a fine option. If you have trips with buddies with other boats, you don't want the large raft anyway, because it will get loaded down and rowing it becomes a chore.
I've fished out of drift boats and other rafts, so I have some basis for comparison. Fishing out the stern of a maravia isn't like doing so in a clack, and I generally put the lighter and hopefully better caster in the back.
My bud has a Sotar that is a larger than the maravia, but I wouldn't trade for a couple reasons.
First, the spider is easier to maneuver and lighter than the sotar. We've hoofed the boat down the Revenue Bridge put in on the Sandy, yanked it out on the side of the road on the Yakima. Fun? Not really, but easier than the sotar, which is bigger, less stiff and more awkward.
Second, there is huge difference in the floor. The maravia drop stitch floor is solid and I can stand up on it without the trampoline feeling.
Here is a series of pics with the Maravia, I know it's a well trodden story, but I never mastered importing photos. It made it without a scratch.
http://groups.msn.com/JonBial/roguepictures.msnw
As for durability, I don't think you can beat Maravia, but with proper care, a raft should last many many years.
One tip, instead of using rope around the raft, use webbing, it catches fewer hooks.
Of course, if the choice is me row my boat or my buddy's boat with him on the sticks, I'm happy to ride in a sotar
Happy boating,
Jon