I don't think there is one specific metric. It seems like SVN commits would be more accurate than LOC, but when I hear numbers like that, I begin to seriously doubt it. You have to take a lot of things into consideration when trying to measure "forward progress".

In theory all of our commits are approximately one feature, and I can't, for the life of me, imagine finishing 100 features in 2 days (even split between all three of my team). Clearly there's some disconnect between what different people consider to be a feature.

For the record, we've made a little over 1000 commits in the last five and a half months. I certainly don't think that makes us 20 times less productive.