Hi geocycle,
A Blackburn carrier and size 11 (46 Eur). I had size 461L RST 425 mm chainstays.
I tried our Altura, not particularly large panniers, and they would always catch my heels.
Different panniers and a different rack that puts panniers further back might have worked, but I wasn't going to experiment.
425 mm chainstays are usually on fast touring bikes. I just felt "crowded" if that makes sense.
By the way that was not the reason I sold the RST.
Steve