A-flex vs C-Fles

Can anyone help me understand the difference between RemStar's A-Flex and C-Flex? I've used a RemStar with C-Flex for 5 years and LOVE it - alas, it needs replacement. Try as I might to understand their website, I just can get the hang of what the difference is. Has anyone used both and can tell me what difference there is? Thanks!

I was told that the difference was a reference to whether the machine is in auto mode, which would require Aflex as the higher the inhale pressure the corresponding exhale pressure also goes up, versus, If you use the auto machine in CPAP mode, then it reverts to the Cflex that you are used to.

I think you want an auto machine, even if you do not need it now, one never knows what they will need a year or two from now, and the machine can help to find the right setting, or make up for a leaky mask, or having congestion. One can use an auto machine in either auto mode or the straight pressure CPAP mode according to how it is set.

AFlex is only offered in Auto mode but my PR S1 Auto CPAP machine also offers CFlex in Auto mode. So both AFlex and CFlex in Auto mode.

In CPAP mode the choices are CFlex and CFlex +

Respironics web site explaining all the differences doesn't really tell how they feel.
I can't put it into words. The differences in how each setting feels. For me it is more of a rhythm. I picked the setting that feels more like my normal respiration speed and force. Settings of 3 seem a little "fast"...like I am being rushed.

Best thing is for a person to try each setting to see how it feels to them.

My very first machine...M series APAP with CFlex.. I couldn't tell any difference with it and turned it off.
My second machine..M series APAP with AFlex... Man, I liked AFlex...setting of 2. Exhale was effortless.
3rd machine PR S1 APAP with AFlex (and CFlex) I used AFlex because I already knew I liked it better, but to be honest did not try CFlex in Auto mode. I have never tried CPAP mode in any of my machines so I can't comment on how it felt.