I haven't used the Milwaukee guns (most of mine are Bostich) but, while around head nail will hold better in teh long run, the only concern I'd have is that sometimes teh round head guns are harder to use in tight spots.
The round head gun uses nail collated at ~21 degrees. The clipped-head gun uses nails collated somewhere between 31 and 34 degrees. The result is that the cartridge that the nails load into it tucked up a little higher with a clipped head gun which makes it easier to get into some tight spaces.
If your basement is wide open I'd go with the round head gun. If it's lots of little tight places I'd lean towards the clipped head gun (of course having both would take care of that issue completely!
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