Well, while we're waiting for someone who owns both, I can comment on the C-Flex - I have two of them for different pistols, and I've never owned a better IWB holster; it's hard to imagine how it could be improved. And, I ordered mine without the holster-mouth reinforce. I wanted mine that way in order to squeeze every amount of thinness possible to increase concealment as much as possible (1911 Gov't Model 5"), and surprisingly I have no trouble reholstering unless I crank my belt up so tight I can hardly breathe. I wasn't in a huge hurry for mine, but Steven's willingness to adjust the cant really won me over. My Sparks SSII was a great holster, but I sold mine after I got my C-Flex.
My logic was/is this - I'm not a LEO. Reholstering with one hand is really low on my list of priorities, and were it necessary I can always put the safety up and jam it in my waistband someplace. As a civilian, my only imaginable need to reholster in haste would be if I have a bad guy on the ground and compliant, and I'm only reholstering because the police are arriving and I want to put them more at ease. LEOs have entirely different issues, but honestly ... I'm going to have to sweat this holster until it rots (or I rot, which is more likely to happen first) before I'll have a hard time reholstering with one hand, and as I said, mine doesn't even have the leather reinforce. I've been carrying it almost daily since last July (2011), and it hasn't collapsed a bit even though I don't mind if it does. I live in the southern Appalachians near both a creek and a river, and since we get little breeze in these twisty hills, most of the year it's very high humidity and fairly hot. Also, I sweat like a horse ... that may be a bit too much info, but we all know that's a tough environment for a leather holster. The only observable difference between my holster and a brand new one is that mine's already broken in, nyah, nyah!