1, if you use the Pi USB port I would think a mR or a uR would be clearly better
2, the ordinary mR (1.3) is not as good as the ultraRendu. The 1.4 version of the microRendu (now only available in the used market) is closer to the quality of the ultraRendu, but the uR is the best. In addition there is now the opticalRendu if your network allows fiber optics.