Can't say about slowe350, but in my case lift position is not the issue, weight of load is. Behavior is the same 6" down as at the highest lift point. Have not worried about the behavior since gaining a few rpms when a max capacity lift load is removed is fairly common in tractors that hold the load constant (my experience is with older MF's) as opposed to those that let the lift drop an inch or two then snatch it back up. Most folks probably wouldn't notice it unless they left the tractor stationary, holding up the max load, long enough for the lift to settle and the pump kick in. Not apparent if the tractor is in motion as the bumps and bounces make it easy for the lift to "catch up".
I have heard that 3 pt. lifts are / were designed to leak down as a safety precaution, ie. tactor is under the shed with one kid playing on the seat and another playing under the gang disc. Course that came from the MF rep as the older ones were known to leak down as soon as the engine shuts down. Fact or good smoke story, who knows.