Greased, caseback tightened and tested is good to go, even if it´s just a simple test in the mall it´s better than nothing.
Generally if they are initially wp-rated for more than 50m by TDs (instead of nil) they will perform well after above procedure.
Personally I will avoid chronographs or anything else that has more additional leaking points (HE valve excepted).
PS: unlike expensive or unique/vintage gens, reps are easy to replace for less than $500. Unlique gens, reps always have the same
A2836 or similar inside instead of a precious movement.
To get some unique perspectives/distortions - You need water