That's a good tip for us penny pinchers.
I have liked all of the Simms boots... except one pair of spiked Guide boots I bought that failed miserably. Premature wear to the rear of the heel cup due a backing of neoprene. They did replace them at no charge though, with a newer better design.
This Vibram sole idea is good for the environment... though not new. I had a pair of LLBean spiked 5/10 rubber soles in 1998 that were great .. until you walk into a conveinence store and its like walking on an ice rink. The spikes with the rubber sole is going to prove to many to be an accident waiting to happen.
So a word of caution - if you have the spiked rubber Vibram or 5/10 sole, do not ever walk on anything other than river, dirt or concrete. (also, many guides wont let you in the boat)
Just wait.. you'll see others later who remark the same.
In the meantime - stock up on clearenced felts! Simms boots at 50% off is a steal!
best fishes, Brian