I think the additional thickness of the new capsules makes the donut sit ever so slightly higher (in a location that hasnt worn in yet). Heat the device and the donut is easier to wiggle out with a poker tool or something. In fact the donut was hard to remove when it was brand new and eventually I was able to remove it by just turning my device upside down with the funnel removed.
I don't have a lot of experience with my bowl unit yet, but I have noticed this issue with the capsule sitting a bit high. When I first got mine, the capsule (and the donut) sat so high that you could barely screw the funnel in place. After trying to fuss with it, I sent it back to Marc for an adjustment. After getting it back I only found a slight improvement and the funnel still barely makes contact with the thread to hold it in place. I even tried taking a fine emery board and sanding down the wings of the funnel to make them a tad thinner. Still, the funnel barely holds in place. I have to be careful when removing the plug during a session, because if I wiggle it in the wrong direction it will nudge the funnel and pop it out.
This is the only real issue I've had with my 9. So rather than deal with the hassle of another return I just took advantage of the 420 sale and bought the capsule plug and an extra capsule. I'll see which way I prefer, but with the capsule plug and no donut I'm hoping the setup is a bit more stable.
I now set up my settings to be 320, 340 and 360. Most of my extraction is in the first 2 settings and I also use the 360 for more of a finish up setting. I enjoy my 9 very much. To quote a legendary FC member, it's a very "civilized" vape session with great flavor on the lower settings. And I agree that since I'm vaping at such low temps I really don't need a significant cooling stem. The little 14mm Jhook I use works perfectly. Still exploring a good stink-proof case to keep it in.