I will tend to agree with this train of thought. I just had this discussion with my service manager who was saying how wasteful it is to toss all that fluid after 50 hrs. Heck, he even talked me into doing the 50 hr service myself and gave me a gallon of engine oil, engine oil filter and both the HST and Hydro filters!
I have a 2620 and it states to change the HST filter and hydraulic filter @ 50hrs, not the fluid. You will get shavings and filings from the oil that falls out of the filter when pulling it. However I drained the tranny case into a bucket and strained it with a fine particle screen......nothing. I tossed the oil I caught from the filters and recycled the rest.
Nice job !!! And sounds like a nice service shop too.