Rohloff / Alfine conversion...

I feel the need for a pre-season workshop project...

I have one of these https://www.bikeradar.com/reviews/bikes/hybrid-bikes/ridgeback-flight-ti-review/?image=2&type=gallery&gallery=0 from 2009. It’s essentially an Ultegra equipped road bike, but with flat bars. It is a very very nice bike, and I plan to keep the frame forever if I can.

I would like to explore the idea of converting it to hub gearing, Rohloff, Alfine or similar. I’m not sure what the latest/best options are. I would like to be sure that I end up with a decent range of gears, particularly at the low end as my knees aren’t getting any younger and I like to ride up hills. If I could lose the front derailleur and go to a single ring, even better. Budget not a constraint.

Thoughts / comments? Has anyone done something similar? What do I need to look for/at? What are the pitfalls?

Thanks in advance!