Multieffects vs. pedals
Should you choose a multi-effects processor or put together a board with a collection of individual pedals? That depends partly upon how many effects you intend to use. If you put together more than a few analog stomps you're going to get some signal degradation when all the FX are bypassed. It doesn't matter whether the pedals all true-bypass or not. Adding a buffer (or a buffered stompbox) is just a band-aid to keep the problem from getting too much worse as you add more stomps.
A lot of digital multi-FX digitize your straight-through signal; again, you'll probably notice some degradation. You can't beat the convience and flexibility of a multi-effects processor, though, if you love effects and hate carrying a heavy pedalboard.
Keep in mind that a lot of this has to do with tradeoffs. Depending on the signal chain you can sometimes compensate for signal loss through pedals by small tweaks to the amp settings and your playing style. And I'm talking about, for the most part, really minor differences. These kinds of differences that'll most likely wash out when you play with a band...
I play mostly solo guitar, so I'm a bit more critical about what I hear. One thing that really bugs me about digital effects is that they have noise gates that mess with the dynamics at the quiet end of the scale. Most of these noise gates are pretty crude, designed mainly to hide the fact that the pedals would otherwise hissnoticeably; the gates really change the feel of the guitar if you use a lot of dynamics in your playing.
Again, like I said... A lot of these differences are small enough to ignore. Your best bet is experiment and find out what works best for you.