Maybe your just being a touch optomistic about the actual release date of Maemo 5. Recent analysts have been *claiming deployment in some areas as soon as late 2009.
There was very limited Wimax availability at the time it was announced as well (I'd say there still is).
I really think that it's the better choice (even if you can't use it for a few months) since you'll be more limited with HSPA than LTE with regards to speed, carrier, bandwidth, max downloads, etc. And I think it's going to happen sooner than you think because big companies like Verizon have so much of their future vested in it.
(I'm sure you'll disagree...since I don't remember you really agreeing with well...anybody)