That is the question . . .

I'm gearing up for my first duathlon this weekend and I'm thinking about whether or not to throw a pair of clip-on aero-bars on my roadie ('00 Trek 2300). I am comfortable riding in the drops for the duration of the cycling section, and I've never ridden on aero-bars before -- I'm a bit concered that I'm not going to feel comfortable on the bike. I could get at most four rides in between now and then to get a feel for the bars; I just don't know if they're worth it.

Some of the guys I work with (I work in a bike shop) think that aero-bars aren't worth it because they constrict your breathing, so that whatever you gain in speed is offset by what you lose in aerobic capacity. I don't buy this argument (if this were true, Lance and his ilk wouldn't be out there on aero-bars in the TDF and elsewhere, trying to pair seconds off their times). Clearly you can still perform at peak levels in a sharp tuck. But can I adjust to that tuck quickly enough to make this investment worthwhile today?

The faster you weigh in on this thread, the more helpful you can be. I have to decide what I'm going to do ASAP, since throwing the bars on is going to set me back, and I'm going to need some time to get used to them.

Thanks for the opinions in advance!
Cheers.