Is it a replacement or are you getting a complete new shower unit ie basin, tiles etc put in? we have a mira elite2 which we've had since 2000 and haven't had a problem so I can't tell you what to avoid in relation to an electric shower itself except for positioning of it ie not too high and not too low, bear in mind the height of the users. But if it is a new unit incl tiles etc, there's a few things. 1 - you can get a fibreglass sealed unit, so as to remove any chances of leaks in or around tiles. 2 - get your grout sealed to stop it going mouldy 3 - get a ceramic base not plastic 4 - our shower happens to be where our gas meter used to be, so we kept the box shape, tiled inside it, so now we have a nice neat area for shampoos etc which does not intrude on shower unit space. HTH