I've noted that the main stream of the discussion is almost all about Photography.
I'm interested to supply GIMP with some advances and improvement to Digital Painting. I'm working on the GIMP brushes, statics and mainly the dynamic brushes since 2007~08.
Some of these brushes are the current stable release and on the git master. With GIMP 2.8.+ I've began study the paint dynamics to emulate some difficult techniques like watercolor and other techniques around or with some impasto quality.
Since 2012~13 with other artists we're beginning study the paint dynamics and howto build good presets and good brushes... These artists including me are: Mozart Couto (illustrator and cartoonist, Brazil), Gustavo Deveze (artist and cartoonist, Argentina), Elias De Carvalho (Illustrator, Brazil), L'ubomir Zabadal (artist e Art adjunct professor, Nitra University, Slovakia).
Something around these steps already knew to Prokoudine mainly. Many of these works and tests I've been publishing on my g+ account... these is the collections around this theme to GIMP since 2014: https://plus.google.com/+AmericoGobbo/posts/Xg2FAoELk46

I've promised to Prokoudine the tutorials around the painting techniques since last year when I've began writing many things to many techniques and how to use the current tools set to improve the quality of the painting. All these studies series need of the good presets and a bug around the workflow of this instance is the great problem if we think to distribute these presets...
https://bugzilla.gnome.org/show_bug.cgi?id=731279

The recent studies around the wet and bloom effect are very interesting and it is possible only using the .gih brushes + paint dynamic + some tool options features... you can see here: https://plus.google.com/+AmericoGobbo/posts/LjjinvWAF8W

Another bug very critical for me is with the velocity parameter of .gih brushes that don't working. My approach is using also the .gih brushes and is important this kind brush will be working well. https://bugzilla.gnome.org/show_bug.cgi?id=748472

I wait some note or comment about this and if is possible to resolve these bugs to think begin to publish the tutorial around painting techniques with GIMP.

My works and illustrations are all made with GIMP and MyPaint. Now I'm working and testing many instances on the GIMP git master to all different approaches around Digital Painting.

http://americogobbo.com.br

The bugs are present in the the 2.8.14 and the current git master. Thanks.

Thanks Adrian to resolve the .gih velocity parameter. I need a bit more discussion around the preset bug...[ https://bugzilla.gnome.org/show_bug.cgi?id=731279] that is, in part, a UI problem.
I think that is possible to resolve it... perhaps a patch: the save button need use the current values and settings present on Tool Options. This flow is a bit complex and I think that the last comment that I had is optimal to understand the problem. Do you have time to discuss it? Bye
americo