Check out these guys at dive soft,
Divesoft s.r.o.
i was dead impressed when i got my hands on one.
it does every thing you will need and loads of other stuff like ammeter and volt meter.
and it doesn't use a He sensor as such but uses ultrasonics, so there is not sensor to be replaced and has a built in mix computer
and on top of this it is a He and o2 analyser in one unit.
kind regards john routley