v10....couldn't wait to get out of it, but Leary of not having g 2nd battery available anymore...
V10 was a phone from an era where LG has truly horrible battery problems. The 808 was a thirsty beast and they had no idea how to keep it from gorging on power. My wife had a G4 and needed a second battery to get through heavy usage days (like on vacation)...
The 2 XL will be a whole different animal. The newer chips are so much more efficient, and paired with a OS that had made huge strides in power management.
And as for the other side of that removable battery coin... It's clear to me that Google made some choices geared to improve the life of the cell (and they even made it part of the ad campaign). You'll see a free complaints that it takes a little longer to fully charge. That's not a mistake, that's because design. They are stepping down the charge current a little sooner and a little quicker... This greatly reduces stress on the battery when it's most sensitive.
The 6P was a lot more aggressive in this regard(thanks to Huawei).. It charged faster and to a higher voltage and the cell wore out quickly. I tried to be careful with mine and it had still dropped 12-15% after about 15 months and I replaced it. It's been 9 months since then and, in the hands of my less obsessive wife, it's starting to wear quickly.
So both I think you'll be pleased with the phone.