If you go with a separate lift motor combo I'd suggest if possible, owning a router with a removable fixed base if it's your only router. If you already have one or more then I'd consider buying a motor only unit for a dedicated motor/lift combo that never leaves the RT. Extracting and inserting the motor from the lift is a pain.
I've never used or seen a plunge with a built in lift, are they also able for hand held work?
I agree with BigJim on the slop issue, my surface planers must be treated as such right from the box. But at least for "MY" Bench dog lift there is no slop that I can tell, (just over a year old). The slop if and when it occurs happens when the direction of the turret crank is changed, e.g., up to down.
The positive up or down pressure on the turret's threaded rod is released as the crank rotation is reversed. The SLOP is relative to the FREE space between the threads of the crank nut and threads of the turret rod and any other gears involved like the pinion gears on many planers.
I think because of the limit on parts involved with lifts the slop is minimal to -0- especially if the tool is kept as clean as possible as often as possible. As for the Bench dog, I'll have to check, but I think the big honkin threaded brass nuts are replaceable.
Never bite the hand that looks dirty!
The more you know the more you're worth