I'm trying to decide between the LM 2101 and the LM 2102SP.

I'm looking to buy my first electric lawnmower, and I'm trying to decide between the LM 2101 and the LM 2102SP. My yard is pretty much flat, under a 1/4 acre, and though I haven't really timed it, I think it usually took about 30-35 minutes to mow it this last summer. Which would model would work best for my yard with those parameters, and would the smaller 5.0A battery give me enough run time if I chose the 2101, or would it be better to have the bigger 7.5A battery? I've also heard about the 2102SP having a better "high lift" blade? Do both models have that now, or just the 2102SP?