I have tried them underhanded. It seems to serve no other purpose then to give the larger biceps muscle more leverage if you come up to the same point on your chest. With that in mind I prefer not to tinker with a well established exercise.

I usually follow up this exercise with dumbbell rows. I do them face down on an incline bench and pull both dumbbells simultaneously. I use 75 lbs for 10 reps and then go straight into shrugs in the same set for another 10 reps. I find that this is a good way to work the traps because the back is exhausted and can not assist as much. I do 4 sets like that. I keep my hands in a neutral position for this exercise.

I then do 4 sets of pullups (4x10).

Yeah, if you draw the bar to the same contraction point, or let the elbows flare-out, then its not so hot. if you 'arc' the bar to come in lower (between the belly button and sternum), and keep the elbows tight to the torso as they travel, it hits the lats with less trap engagement- not realy what you want for functional power, but it can be a fun diversion.

i also like bi-lateral dumbell rows. so many people who do single arm rows get into terrible habits regarding bodyposition, ROM, and use of momentum, so the way you do them, and also T-bar rows as an alternative, I find preferable.
nice superset as well, i like anything that really works the grip as a bonus.