Hello @niko.virta
I bought two RUTC50 and those are working much better than TRB500. CPU loads are looking normal and GSM speed are so much better now. No problems with wan bridge mode.
But there is one possible problem that you should also be aware of. There have been some possible issues with RUTC50 temperatures and those might come problems under heavy loads. Here is link for the thread that have mentions about heat problems.