Be careful. I had H4 hi-lo in my Classic Impreza, and the loom caught fire.
The headlamp hi-lo controller has twin +ve feed to it, and if water gets in (like mine), then the wiring shorts and the fuses one for each side do not blow so it catches fire. I luckily smelt the wiring going, and managed to rip the earths off so it stopped the problem.
But the H4 ones do give a decent cut off as the bulb sits in a shroud, and fires back and fore to do high and low beam.
For MOT they can ONLY test what is there, so if you have no levellers or washers then they can`t test them.
The major downfall is cut off of the beam, as the centre point of the brightest part of the bulb will be in a slightly different place from Halogen to HID, so the cut off will be slightly different, its all a matter of how much out.