about to buy (for the first time) "true" freediving fins; thought it was a good idea to buy interchangeable blades for easier travel, replacement purposes, etc. posted this on deeperblue and response was very negative on interchangeable blades; anyone have an opinion? seems like all of the really expensive fins i look at all have interchangeable blades, so don't understand the the other negative responses(after all, if these opinions were accurate, why would anyone spend $500 on fins that have interchangeable fins?) thanks