I use one and think it's the Mutt's Nuts. Mine will parallax all the way down to about 9 yards, but I have the TMR ret as I don't much like mildots, though the spacing is the same with half mil hash marks added in as well.
I have looked through Big Chris's 10x40 Mildot Leup, and a couple of 3.5-10x40's, and the mildots looked a nice size. They are true mildot scopes, so the spacing is as should be, really.
I don't find a problem with parallax error, but I do use a scope enhancer which helps maintain head position.
The DOF is excellent, with only the really close ones being blurred for me, but I can still manage to shoot 15mm kills at 8 and 10 yds in practise, so it isn't an issue.
Bad points, only one - cost, they're very expensive. Mine cost more than 4 times the TAC 30 I used previously, it's not 4 times better, though, so it's a case of diminishing returns when spending that much money.
Actually, two bad points, when you look through a "normal" scope you think it is sh*t. I recently spent a couple of minutes trying to focus my Viper at 25yds and eventually realised it was focused.
The fixed mag model is built like a brick sh*t house and , the built quality really is 1st class. The MK4 also has a lifetime warranty, that says they are confident it isn't going to fall apart or let you down.
Hope this helps.