I've been switching over to Better Bottle for a few reasons.
First, it's they're a lot lighter. I cart mine up and down the stairs and the extra weight of the glass is noticeable.
Second, safety. I've heard enough horror stories about dropping the glass that I'm not willing to risk it anymore, since the Better Bottle is a good alternative. Sure, most people don't drop their carboy. I just don't feel the need to risk it.
Third, I bought the ported Better Bottles with spigots. That means I don't have to use a racking cane to move my wort/beer around anymore; instead I simply open the valve. It has an internal spout that you can rotate away from the trub, so I don't pick up anything that settles to the bottom.
Ultimately, I feel the Better Bottle is a great alternative to the glass carboy. It can be cheaper (unless you get the ported bottle + accessories like I did) and I have not found then to produce any adverse effects on my beer.
I have kept my glass, and I'll likely use them if I'm aging a beer for a long time, but even then, I'm not really worried about the oxygen permeability. Again, I haven't found any adverse effects.
One not about scratching: I have never scratched a better bottle, but you WILL scratch it if you use any sort of brush. To clean the trub you can soak it with your cleaner of choice. Again, I've never had any troubles cleaning, and I've never scratched it.