Granted I'm still just an MSIV, but I've experienced both systems. I made sure to do my sub-I at a site that used q4 as I thought this was better as you get to see your patients from start to finish and learn more than with NF. However, 30 hours shift are LONG. At least for me, I really don't learn anything after I hit my "wall" at about 2-3am when on-call. And rounding on the Sunday morning of your black weekend is just so painful.
I feel like I've been "hardcore" long enough. I'm tired of hearing this you're not man/doctor enough if you don't take 30 hour call on a regular basis. I'm very happy that my future residency uses a nightfloat system. I know I would feel better as a patient if my doctor hadn't already been awake for 24+ hours when s/he was making medical decisions for me. I think the key issue here is making sure that sign-out is complete and accurate every time.
Just my $0.02.