When you can do that with 45sec recovery (re: Wohlhuter) get back to us. (LR troll!)
I know sprint guys who can do that, yet can't run 800m worth s**t. (another LR troll)
Do 2x400m (1min rec, or max 3min) the latter is the Kosmin test if done as 1 minute reps, if you really want to know.
It will depend on your endurance capability as well. I coached a HS guy who ran 1.50 in G12 and he couldn't do that (49.4 PR)session (Or at least didn't anyway), but he did run a 600mTT (solo) in 1.21.8, going through 400m in under 54 - I felt that he was in sub-1.50 shape (won all his major races) but he didn't contest his final, and best, opportunity to find out.
To answer your question, why so much recovery? what was your 400m PR? see above about aerobic shape. In other words you haven't given enough information to make a valid determination other than your PR of 1.50. Do YOU think you were fitter than 2009 (based on the training you did prior to the injury)? How many races does it take to sharpen you into PR shape? (out of the gate, later in the season, etc.)