Yes, There is sometimes solder clogging without the flute, I can not remember if that also was the case before I modded the tips. But before that I had to empty the tube much more often and had to clean or replace the felt-filter in the tube more often, sometimes 2 or 3 times a day while there was not a lot of solder in there. That was sprayed with solder and flux, that was more work as removing the clogged solder. Now I have a Z shaped piece of metal clamped just before the felt filter. It is bizar how well it still sucks with the tube almost full.
There is a simple solution for the rubber, (I think) If you make the part of the tip that is in the heater a bit longer so the thick part of the tip also presses on the front side of the seal. That way you have an extra and much better sealing. And an even better thermal resistance because of the increased mass.
But I think I desolder a bit more as average because of the sort of repair work I do.
Nice image!
We've tested this same type of design previously, and there were 2 big issues: First of all, we try to isolate the heater front the handle as much as possible, because of heat build-up - this type of direct contact causes the front portion of the grip to heat-up considerably. An overly hot handle is something we try to avoid at all costs.
The second issue we ran into was Front Seal failure. The main failure mechanism of the current Front Seal is where the fluted end of the tube goes through the hole in the seal. The heat transferred into the seal hole makes it much more brittle and it starts to widen. Then cracks form around the hole and you lose vacuum. With normal use, the Front Seal may last a year or more, but in heavy use, or when you switch out tips frequently, it may last only 2 months. When we used a direct contact method, the entire middle part of the seal (where it had direct contact with the back end of the tip) became brittle, the hole widened, and the seal against the Solder Collection Chamber was lost. This seal only lasted a couple of weeks.
But I think it's a good idea to re-examine the fluting of the tip's stainless steel interior tube. Maybe a combination of cutting the tube and higher temp silicone will do the trick.
Aaron