So in my looking for a new bike I've run into some curiosity on how feasible it would be to swap the IGH on a bike. I'm tempted to get a Priority Bikes Classic Plus Gotham, which has a Shimano Nexus 3 speed IGH, but I'm not sure if that will be enough gears, and if I'll get annoyed with it down the road. How viable is it to swap that hub out with a Nexus 7 or 8 or Alfine 8 down the road if I want? I realize this would consist of taking the old hub off and dropping the new one in (with needing to redo all the spokes), but is this viable? I have no idea if there would be frame differences, or other things I need to consider.