I think you should check out the Recharge Mower 20" Lithium. This has 10.5 Ah and 36v. Super Powerful. More money than others but after using it I was sold. Blew all others away.
Thanks for your post and welcome to the forum. It's good to hear from another lithium ion powered mower fan. Yes, I am familiar with the Recharge Mower PMLI-20 mower, but passed it up for the Greenworks mower because of the high cost of both mower and battery as well as its short 1 year warranty. The PMLI-20 costs $280 more than the Greenworks and the battery alone costs $400, which is the same as the Greenworks complete mower with batteries and charger. The Greenworks has a 2 year warranty on the batteries and 4 year warranty on the mower, and the batteries cost half as much. Although the battery on the Recharge Mower will probably last more than a year, it's scary to think that I might have to spend $400 yearly to replace it.
Another problem I have is with run times. The Recharge Mower states that runtime is "in excess of 45 minutes," which could mean 50 minutes or more, but if it's less than an hour, then a spare battery would be needed. At $400 for a spare that's a bit steep for me. The Greenworks promises "up to 70 minutes," and I could buy an extra 2 Ah battery for $80 to extend the run time about another 20 minutes if need be.
Finally, the wheels on the Recharge Mower PMLI-20 are rather small, 6.5" front and 7.5" rear, whereas they are 7" front and 10" rear on the Greenworks. I can live with small front wheels, but I really like large rear wheels on a mower.
I think if Recharge Mower offered a better warranty and a longer run time, then it might be able to justify the higher price.