No won't take any time at all with mesh. In fact far-far quicker to build, texture and animate than with the existing methods. Easily make a new complete avatar in an evening, taking your time (if you are experienced). In fact, I'm guessing that the market is going to be overwhelmed with new stuff, as newbie modelers grab all the free models off the web and upload them to SL. Sadly, most of the free stuff on the web, 99% of it, is junk reject quality full of errors made by newbie attempts to seem pro at something they made with crayons, glue and glitter sparkles. But there are some good 3D artists around these regions.
Anyway, mesh is probably one of the best things the Lindens have pursued, and once it's complete it'll no doubt blow your mind. In the meantime, it's in beta, which means lots of stuff has already been built and just waiting for final. Now is probably time to build your tinies
Oh and just to add/edit in, if you don't know how to model now, then now is the time to learn. It really does take a lot of time, we are talking a couple hundred hours of study and practice to even begin to become good. I've tutored a bunch of people on a personal basis, and it takes months before they start to make good models. And I don't just mean looks, but actual composition without errors, it's easy to make errors and not even realize it until you get better or someone points it out to you. I'd suggest, if you start the free rout, to get Truespace 7.6, because it has a huge amount of professionally made tutorial videos for free and exports COLLADA. Don't just play around with it, but follow all the videos, their great, it's the only way you will get any good at it. 90% of people that pick up a modeling app drop it within a few weeks, and most probably because they had no real direction, just played around until they got bored of frustrated.