I came to this thread hoping for some revelation on how to keep feet dry; instead i find the same gripes i have.
I commute 5 days a week and have just started wearing my DeFeet overshoes (as well as DeFeet Woolie Boolie socks) to keep warm. They're decent for keeping tootsies warm but in no way waterproof. They fray easily and with constant use will start to split and separate within a few months. I tend to sew them back up but it's a pisser and, honestly, i wish i didn't have to do it simply to keep the warmth around my feet.
I cannot recommend BBB overshoes for constant commuting at all. I have had three pairs of the HeavyDuty ones in 5 years and they fall apart at the seams as soon as you look at them. I have spent many many nights sewing them back together. It got to a point where i was transplanting older pieces of the neoprene shoes to the new ones to patch up holes and where the seams had come apart. That said, they are relatively decent at keeping the wet out when they're sealed. YMMV, and bear in mind i am a thrifty bar-steward when it comes to kit.