Sailfish OS on Nexus 5 looks and works very good. I am using it as my primary phone. I don't need any Android apps (thanks to you for whatsup). If I really have to use an android app for something, I have a dual-boot setup, so I can just boot in Android and do what I need to do, but I haven't had to do it for a long time.

The screen getting unresponsive to touch is the only additional annoying issue. It will take a reboot for it to fix. Some days I end up having to reboot couple times. (I hear there is a solution being worked on, but have not tested it.) I would really hope the bluetooth issue will be fixed soon also, since I would use it.

Overall better performance and 4G connectivity in US makes it a better choice for me than Jolla phone.

You can always test your app in SDK for Jolla resolution and Nexus 5 for higher resolution. I think it will be an additional benefit for buying Nexus 5 for development, so your app will look better on higher resolution phones/tablets(?).