Thanks for pledging !
The TRS boards are for professional grade sound quality. They are balanced and powered. What this means is that they have active filters which keep distortion low. Because they are balanced, they are able to keep noise very low.
This means that if you require professional performance, you can get it with the TRS breakout boards. If you don't need this quality and can settle for something which lets you plug RCA to RCA, then you may not want that functionality.
I will add, that the TRS breakout pledge on kickstarter includes the RCA breakout boards as well, so you can't loose !
Check the Ultra 2 sound card - use our shop instead of Amazon Europe (Amazon USA is live).
Sound card for the Raspberry Pi with inbuilt microphone : www.audioinjector.net
Audio Inector Octo multitrack GPIO sound card