I'm picking the Police bike up today! I'll keep you posted.
I'll also be adding a Bosch Nyon color, center-mounted screen with discrete remote. I ordered the Nyon retrofit kit for $355 from Merlin Cycles in the United Kingdom. Swapping out the Purion controller seems to require removing the drive unit for the cable run (video: https://www.e-bikeshop.co.uk/Bosch-eBike-Support), which I'll likely seek help with rather than DIY.
The Nyon is apparently not offered in the United States and so yes, I'm a little concerned about warranty. But its plug and play, so I don't actually agree that warranty should be affected - even though it may be.
I'll also be swapping the seat and seatpost with a bontrager gel and a bodyfloat 2.1 once I determine how long the seatpost needs to be.
Oh mamma, you are making that bike into a sweet ride indeed. Some of the forum members here in the US also ordered the Nyon interface from overseas and they have indicated the same, just plug and play. I really was never a big fan of the Purion interface due to the sticky buttons. I would opt for the Intuvia as an upgrade. Obviously the Nyon is the way to go with virtually endless amount of options it has to offer. COBI seems right up there with options, however, I have seen some bugs associated with that interface.
Looks like the bodyfloat is a nice upgrade for the Police being it is a hardtail. I think your upgrades are spot on for that bike. I guess we shall see how those stock tires hold up if you decide to stay with them for awhile. Thanks for the update!