I'm a crusty old plumber that doesn't believe epoxy relining is a good choice for water supply pipes.
My one basic concern is there is no way to verify that it can or has worked until the job is done. Then there is also no way to verify that the inside of the pipe is completely coated offering total protection against further leaks.
I am a big time advocate of relining sewers however as that work uses a fiberglass liner and it is easily inspected before with a sewer inspection camera to determine the viability and afterwards to inspect the outcome of the job.
In your application it requires faith and luck.
If you have it go ahead!
The fact that you have multiple hot spots under the slab says you have several leaks going on and repair is probably not the best option.
I would highly recommend consulting a plumber in your area that is highly experienced in PEX repipes and you may be pleasantly surprised at the techniques he uses to pull off the repipe with as little collateral damage to walls and ceilings. A plumber that specializes in work of this nature often has some very creative techniques they use.