While having the DPOCV (check valve) vs not having them debate will probably go on for eternity, one of what I think is a big factor in not having them is that while you are grading, how often does a person go between adjustments? 2-3-10 minutes? If your control leaks so bad that it effects your grading, then you need to rebuild or replace the valve IMO. It is a HUGE plus to be able to have your side link float. Now I know that not all rear remotes have the float function and for those people there is no advantage to having a side link without a check valve.
Another thing that I will bring up is that none of the OEM units have the check valves. Not JD, not Kubota, not Case, not Massey, not even CAT. None of the AG or industrial machines have the check valves, why? Because it has been made into an issue that in all reality is a none issue. Do the hydraulics move and or leak down, yes they do. I know on my own tractors I have checked to see just how much they leak in an hours time, it will vary from 1/8"-3/16" over an hour. Is that enough to really make a difference when in use? Not with anything that I do and like I've said before how long between adjustments anyway, a few minutes at most. The few thousandths of an inch that it might drift is so negligible that it is hard to believe that anyone can actually see the difference. Again if it drifts enough that it is a problem, then most of the time the control valve should be looked at and taken care of.
My argument applies to grading, it is a different story regarding farming where you do leave your implement and hitch in the same position for hours at a time.
Nothing wrong with either way of having the links, but there are benefits to each.
