Separate pump, or all in one unit?

[amj]

I'm planning to refurb two upstairs bathromms and want to boost the shower pressure that is currently rather weak gravity fed. What factors should I consider in choosing between (a) box-on-the-wall units with integrated pumps and (b) a separate impeller pump feeding both shower heads? I have a normal (non-combi) boiler, cold water tank in the loft, and HWC next door to one of the bathrooms.

Thanks

[namsag]

Pump in the box units usually have more than enough pressure for most people and cost to buy about £140 from focus etc which is cheaper than you will get it from a merchants.. They are generally quieter in operation than a seperate pump unit and on the whole they are very reliable. Newteam where the biggest manufacturer but have been taken over by bristan