Dear DRG.
I will be glad to help you.
The second name of glider G-11 is name G-29. G-29 there was its name in the course of working out of projects, then it has received the name by quantity of transported commandoes of 11 persons - G-11. This glider is easier for finding by name of G-29, than G-11.
http://easyget.narod.ru/air/g_11.html
http://www.avia-rest.ru/g/g29.php
http://www.airwar.ru/enc/glider/g29.html
In descriptions of this glider it is said, that this glider was not made since 1945 for 1946, but then it made till 1948. In these descriptions of history of a glider there is nothing about when this glider have removed from arms.
I have looked data in other gliders were on arms and have found.
In the description of glider C-25:
http://www.airwar.ru/enc/glider/c25.html
Here there is a description that after glider tests in 1948, in 1 year gliders G-11 have begun have removed from arms of Red Army. And in 1951-53 replacements of all gliders on Yak-14 have begun. I think it were possible to tell with confidence that since 1953 in Red Army only Yak-14.
Yours faithfully.