I am using Powerwinch model 712A not on a boat trailer on a silage feedout trailer instead, loading big round bales and it gets plenty of use use over 300 bales over 3 months of the year.
I have worn one of these winches out, it did over 10yrs of use, thats over 3000 loads it was still operational but the bearings had got very worn I replaced it instead of rebuild, it had one set of bearings replaced during its life and a few other small things you would expect with this amount of work I don't think its a fault with the winch just the usage and road dust mud etc from the work I have put it too. I have learnt to pull the covers off now and then and get some grease into the bearings,they are open ball races. I also have had no trouble getting parts.
I have replaced with the same brand and model, the new winch is now into its 3rd or 4th season.
With the use I have been giving these winches I get about 1 1/2 seasons out of the wire before replacing, this season I am trying a soft rope for the first time have only just begun using it this winter and seems to be ok so far but have removed the "wire leveler' as it is not needed on soft winch rope.
These winches have provision to put a manual handle on, I have only used the handle once.
They make a range of winches so you need to look at the specs for what you need.
Hope this helps ask if you need any more info