Assos owners, I'm asking for your opinions.

I'm about to buy a new pair of bibs. Most of my rides are in the 30-50 mile range. I have a set of Assos FI.Uno bibs that I really love, but occasionally, when I ride longer distances, I get sore sitbones.

I'm wondering if I should spend the extra money to buy a pair of FI.Mille bibs. I've done a lot of searching the threads, and I've seen people say that the Mille's are better for longer distances. I need these bibs for everyday riding as I will only have 2 pairs (the Uno's I currently own and the new ones), so I'm not looking for something I will only use for long rides. Are the Mille's also good for shorter distances since 90% of my rides are 50 miles or less? Or should I just get a second pair of the Uno's I know and love, and deal with some pain when I go for longer rides?

I will be doing the MS150 and a few Centuries this year if that helps.