I'd say hydraulics are far superior to chains, that is what we have anyway. Yes they can break down but so can anything mechanical.
As for tips, don't know if this is an existing building or a new one but if it's new and if you go hydraulic, work out where the ram boxes will be and put soil pipe under the concrete to run the pipes through. Try to keep the distance underground as short as possible, i didn't, and i also have pipes runing to 2 ram boxes in the same pipe which can make it quite a struggle getting pipes in and out when you get a burst.
The only other problems i have are with the magic eyes which stop the scraper at the end of the run and the solenoids on the ram which control which scraper runs. Neither are ridiculously dear and i can easily change them myself. You might get a bit dirty but i'm sure it won't be the first time and it's far from the worse job you'll do, infact if there's a hosepipe at hand it should be relatively clean.
Mine are MALGAR but i think they all work on the same principle.