I rode a connondale bike equipped with Rohloff speedhub for couple of days. I still hesitate to join Rohloff's community. It is difficult to compare speedhub with derailleur system. It is just different and you must try on before making decision.
Pros:
1) almost maintenance free set-up which works well in a muddy terrain
3) no needs for adjusting shifters
4) stronger wheel
5) better correlation between cadence and gear than in derailleur system
6) smooth shifting
Cons:
1) Heavy - adds more than 500g in comparison with derailleur
2) Speedhub needs some break-in time (about 5000 km) in order to run in
3) Speedhub seems to be not as efficient as derailleur on gears 8-14. It means that on uphills you will feel distinct drag due to friction inside the hub. That is my most concern because gears 8-14 are about 2% less efficient than 1-7. I don' think that after 40000 km speedhub on gears 8-14 will be as smooth as derailleur
4) Shifting on loads on pedals is impossible but this is not big problem
Some article about efficiency which is worthy for reading:
http://www.ihpva.eu/HParchive/PDF/hp55/hp55p11-15.pdfI hope that helps.