Whatever it does, it does not do it well on Windows with the 2.7/2.8 serie as none from Linux reported that unbearable tearing that even from your video you strong system is still affected by (really it does not annoy you to work on a texture for a hour with this tearing continuously and that seem to get worse with the time ?).
At least my very good 2.6 is completely unaffected for when i'm just wanting to throw my monitor through my window while trying to work on my textures.

I like the new things of the new gimp. The 32 bit color support, the folder layers, the inktool (has been improved a lot).

2.6 is faster even with brushes. 2.8 have an issue that is a little slow in that, also with eraser. Not to mention with bigger resolutions, and it's good that brushes also are bigger. That means that Gimp is prepared to the future, but seems that is not ready yet. It's kind of sad in that way.

Another issue is that color picker's color wheel don't work. There is the icon, but you have to go to the tool box.

*I have to complain for all versions of gimp about a following feature, For example: I have drawn a face that I like it in a layer where are another drawings that are good, but the recent face is in the wrong place. So, I use the lasso tool to move only the face, but when I use the move tool to only move the draw of the face, The WHOLE LAYER MOVES. To solve that, I have to cut and paste the selected layer, to create another layer, then I can move it and merge it again with the original layer where the other painted objects were.

-The problem is when there are a lot of layers. So you can't handle with it in a productive way.

*Another Issue I have to complain is about ABR brushes, there are versions for gimp also, BUT, there are not versions for the gimp. When that pack of brushes are from 3 to 10 it's ok. You open them with ABR viewer, export them as png, open individually in gimp to save them as gbr, and that's it.

-The problem is when there are 200 or more brushes in an ABR, you lose a lot of time, and it's even worse when you have your time scheduled, and you need 10 or 20 brushes of that pack, and find them is like hell where there are the 197th or 94th in the pack. The tag in brushes helps a lot!, but to have that brushes in your brushes is problematic as hell. There is a plugin of abr to gbr generator, but for linux doesn't exist or I haven't put it to work. If you can open the menu to import abr bushes and convert the brushes you need or something related, it would be like magic.

Only to finish my complainings . . . You know a page or forum where I can set or have a graphic Express Keys software for wacom in linux as in windows or mac are? In ubuntu existed in version 10.04, but nowadays the recent version is 13.04 and I could not find another distribution to set the keys. In terminal never worked for me. I set only 1 key and the rest doesn't work, so I have to open terminal launch the xsetwacom and set the other key, but only set that key and the rest doesn't works again. It doesn't anything with the gimp, but, you know If gimp would have that module integrated would be incredibly great. We illustrators would glad you and support you. Not Use photoshop anymore would be out of this world.