I'm thinking of Lithium too.. I want to replace our old AC model (RYOBI 137R).
Motor is at the top end..
I like it okay, but my wife doesn't like dealing with a 100 foot extension cord..
I want to get over to home depot to look at this one..
Ryobi 18 Volt Lithium String Trimmer
Model # P2002 Store SKU # 663831
There is a going to be a lot of difference in performance, but I think she
is going to like the less fuss of wireless..
My daughter has a small lot, and she might like the extra HP of AC power.