It certainly makes going to confession that much more convenient -- especially considering the people who need confession the most are the ones who can't/won't get to Mass 1/2 hour or 45 min. early so they can be first in line.
I think many times the priest "pauses" the confession line during the Consecration, then resumes afterward.
Anyhow, I've seen this done at MANY traditional chapels, including the Seminary. So it must be perfectly OK.
Matthew