Yeah, and nobody has even asked whether this is for open-heel or full-foot fins, diving wet or dry, and what kind of boots. All of those will affect the answer, so nobody has given a good answer yet except Diesel298. How can you guys expect to get properly fitted in gear without trying the **** stuff on? I have two different pairs of TwinJets, different sizes, depending on what I'm wearing. I would not have known what to get without trying them on. That's even more true for the booties and I could not have known what size fins work until I knew what size booties to wear. There are too many variables, even on something that seems as simple as fins, to do this with an online store and discussion board advice from people you probably don't know, who haven't even asked the right questions to give a decent answer.
And by the way, TwinJets have very secure, easy-to use straps and buckles (unlike the nasty straps on the old Jet Fins), so the spring straps are not necessary and a huge waste of buckage. Buying the spring straps would easily eat up the difference in price between an unauthorized online dealer (because Scubapro does not permit online sales) and the price at the LDS.
Oh, another thing, Scuba Pro has started to put serial numbers on their fins, so they can tell what is being sold grey-market through unauthorized dealers and what is covered by the warranty. I haven't heard of very much need for warranty claims on fins, but if you ever have a problem with those grey-market online specials, forget the Scuba Pro warranty: you have to buy from an authorized dealer,which means an LDS.
Doesn't the fact that the online sellers couldn't tell you what size to get tell you anything?