I have spooled up my synth. line neatly under tension and loose.
I lean towards neatly spooled because I have 125' of line vs. the 100' that came with the winch. I havent had a problem yet with it getting tangled or crushed when winching or unspooling.
I always freespool to get the cable out. I've never had to power-out the line.
I would think that if you arent careful spooling the line back in, it will eventually get tangled or build up too much on one side of the drum and cause issues.

BTW..
If you want Masterpull winch line, let me know.
It's a good discount.
Others here have had good results with it.