I have used the LTP aerosol stuff loads of times. It works well to seal the grout and help keep it clean with all those coloured body washes thesedays.
Infact, used it in my own shower area about 6 yrs ago on the main grout and on some small slate mosaics. I only need to give the grout a quick clean down (with diluted bleach! i know i shouldn't but im too mean to myself to by a proper cleaner!) about twice a yr, then re spray it and it stays nice and white.
Definitely worth using IMO.
Another story just remembered about. Had tiled a large kitchen diner knock thru job couple of yrs or so ago and finished intime for Xmas. Went back in new year to tile the utility. Customer tells me he dropped the flipping turkey out of the oven all over the new flooring. Fat juices etc all over the place. I had treated the floor with this sealer (LTP) and you couldnt see any sign of such a spill. Granted they cleaned it straight away, but im sure this stuff helped!