In reply to HB47:
I'll add my 2p worth on other brands.
I've used to have a Optimus Nova, and now own a primus Omni-fuel.
Of the two I far prefer the Omni-fuel, build quality is far better (I had to send my nova pump back twice due to it falling apart), and the fact that you can use it with gas canisters as well as liquid fuel is great IMO. I've found the omnifuel to be very efficient (esp coupled with a ETO Power pot), but there isn't as much adjustment on it as with some stoves. Though I more find this in the upper range than the lower (i.e. you only get adjustment up to so 3/4 of the number of turns, then no change). Between the two valves I find I can simmer very easily.
Plus the omnifuel (and the nova) have metal pump units rather than plastic - broken pumps seem worryingly common with some MSRs!
Cheers!
Stuart