My brother has a TRT 600 in his Ikarus C42 "permit aircraft". It's about 3 years old now and has performed without any problems.
I recently had to install a new transponder into my RV6 and chose the garmin 328, fantastic bit of kit.
I have noticed that the LAA won't approve any further radio installation at the moment with a filser transponder, lets hope they sort it out soon.