I think we're talking about reentry after taking a swim here, because either you don't have a roll or your roll failed. And I think we're talking about having a body type that makes a standard paddle float rescue difficult. If those are true, then I'd suggest:

1. Reenter and roll.
2. Paddlefloat rescue with a heel hook: http://www.seakayakermag.com/2011/April11/burris.htm
3. Straddle/Cowboy -- with practice it's easier than it looks, but you need to spend lots of time on balance exercises, which is actually good for kayaking, too.

I'm not aware of any self-rescues that are impossible or become very difficult with a lifevest on. It's always better to have it on, especially around cold water.

Braces:

Low braces can upright you very quickly and high braces are effective even if your boat is on its side and your head is in the water.

Questions:

if you get flipped when wearing a PFD in a kayak you presumably aren't going to roll all the way. I didn't see this demonstrated. Does the boat go half-way so you can simply brace back up again, or does it fill with water, as seems logical if you aren't using a skirt?

If you get flipped, you go upside down. Sometimes, if you want to roll back up on the opposite side, depending on the boat, you might have to push a little to get the boat to move a few degrees, but usually you're right upside down. Without a skirt, depending on the boat, you'll get a varying amount of water in the cockpit.

Learning rescues on your own from videos sucks. Take a lesson and you'll reduce your learning curve from days to hours. It's worth the time and money.