Are many people fitting these?

if so, which ones.

I know you can get pressurised one with a piston in and gravaty feed ones

do they work ?

moroso

diagrams

ive got one on a Bird engine, if it will go round Gerards at Mallory with a standard sump, (birds do blow) 21 times in 18mins at full chat then i think IMHO you can say they work, will be taking car over soon for some changes, the guy i'm taking it too has two, or did have last time i was there (he's now gone dry sump)(not because they did'nt work, too lower the engine) will get a price for you if you wish, there very easy too fit, i run a manual valve on mine you just have to remember to open the valve before you drive in anger, also very handy for "pre oiling" the engine before you turn the key.

sounds like a plan !