Sailfish Maps admittedly has one nice feature where you can add a picture to your saved locations. Perhaps that's the killer feature that would make everyone switch to Pure Maps.

Honestly though, I think Jolla should dump Sailfish Maps entirely and distribute Pure Maps as the 'official' Sailfish map application, bypassing all Harbour restrictions. They wouldn't have to spend any more money, time and other resources on developing their by now long lacklustre maps application any further. I don't think the license would be problematic either because Maps isn't technically part of Sailfish as it isn't included in the default bundle, you have to install it manually.