I run the SMG/Sonore setup and just added optical units purchased from Amazon for $150.
Basically the TX/RX come in pairs, for about $60/pair. I used two pairs and have them between the switch and i5 and the switch and UltraRendu.
I can't say how it compares with the Optical Rendu because I've never used one. SGA was going the send out an OR for review, but so far that hasn't happened.
I ran the optical stuff to hopefully treat frequent crashes requiring resetting of the UR, i5 and Roon server. I don't have enough time on the clock to know if the crash problem has improved. I can say that installing the fiber system was a breeze, it's plug-and-play. It also keeps the UltraRendu well away from wifi, which was SMG's recommendation.
I like the SMG/Sonore stuff but it hasn't been trouble free. There's a review here