I always take the use year into account when I rent (have done so about a dozen times now) because in the event that something might require me to reschedule a trip, my flexibility for rescheduling will depend on the use year.
Your points provide an ideal example. I'm looking to rent points for a visit in late January of '10. If we were to make a reservation using points from the '09-'10 year, and then I had to reschedule, my points would expire within a few days of my reservation - unless I was able to reschedule several months in advance, it would be too late to bank the points.
On the other hand, if we were to schedule such a visit using points borrowed from the *following* year, then there would be no way at all to reschedule, since borrowed points can't be "unborrowed".
I'm not saying this to be critical at all, but just to show why the use year will make certain points a good fit for some renters, and not so good for others. In my case, I'm one for whom they're not such a good fit. Since BLT points are sure to be extremely popular, I have no doubt there will be plenty of others who will want them.
Since this isn't supposed to be a discussion board, maybe we should not pursue the discussion? Whatever the mods say is all right by me.