If you were to convert to a pressurized system you would benefit by being able to refill the system quickly,clear air locks easier and get up to the 1bar of pressure the boiler manufactures look for, the down side is it may show up leaks on your system as the pressure could drop and you would have to keep refilling, that is if there is a leak, in respect of the price, get other quotes, it sounds a bit much to me, but i don't know what your installation is like.
I think thermostatic rad valves are great, they will help balance your system, they give you more control and they save you money, a couple of tips, don't have a trv in the same area as a room stat, leave a least one rad with out a trv to help the boiler with circulation.
If you are going to the trouble to fit trv's, have a look at your system water if it's black, brown or has solids in it have it flushed and have a inhibitor poured in to it to keep things nice and clean inside rads and pipe work, Gary.