I have a Dynamis system which is not used primarily for my G scale locos BUT
I did try it out of curiosity and I was surprised to find that it worked jsut as well as my MTS system... granted I did not run more than 2 locos at a time, However I dont usually run more than 2 with the MTS!!
I also found that I had no problems using the dynamis to programe the loco decoders, I did not experience any problems with LGB factory fitted decoders, ones tha I had fitted myself or Massoth decoders
But I personally would not rely on the Dynamis for everyday running of a garden line, as the infra red communication is not 100% reliable outdoors, it is possible to upgrade the system to a RADIO control system but that adds to the cost.
Personally I would recommend MTS or Massoth ( but of course these are expensive) there are quite a few being offered on the S/H market currently as some G scalers seem to be selling up!,