I just use a small square of blue ccf wrapped with aluminum foil. It has worked really well with both gas and liquid fueled stoves. The only problem I've ever had was with using Esbit on it where I melted a bit of foil -- which was easily replaced -- and scorched the ccf a bit.
For the record I own both white gas and Powermax stoves. There are pros and cons to both, just like any other piece of equipment.
I'd say white gas stoves are more dangerous since you have to pump and prime them; both operations have their incumbent dangers. One time I over pressurized an XGK (easy to do with the old gray pumps), and a bunch of fuel burst out around the O ring at the base of the pump while the stove was in operation. The results could have been quite disastrous. Fortunately, I was using the windscreen, and the spilled fuel did not ignite. (it's just as important to use the windscreen for safety reasons with a white gas stove as it is to use it for efficiency reasons). That close call not withstanding, I have used white gas stoves since the 60's and have never seen anyone get hurt.
Powermax stoves are such a snap to use, but the connector is vulnerable. I've seen numerous failures where the cam didn't engage properly, and I haven't seen that many Powermax stoves. If I in my limited experience have seen so many failures, I think it's fair to say that the connector is a Powermax stove's "weakest link." Carry spare connector parts (the cam and the piece the cam fits into) and you should be fine. Said parts come with the standard maintenance kits.
Lastly, a point of information: There's nothing inherent in white gas stoves that prevents them from simmering. It really depends on the stove. The Optimus Nova, Primus Omnifuel, and MSR Dragonfly all simmer very well just to name a few.