So was I!! Great minds think alike . . . Certainly don't make any major changes, or purchase different kit, until you have thoroughly settled on the saddle, posture sorted etc etc.
Weight - yes, Rohloff bikes do feel heavy at the rear, but I would be surprised if the RST was significantly heavier than comparable bikes, bearing in mind the rack, pedals, etc that is often left out of published manufacturers weights. And if it is heavier, it makes less difference than you expect - I used to ride a Raven Tour, heavier than the RST, and surprised myself (and others) with how well it went. And if you regularly ride on trails, and in situations as in the photos, you will find that the RST will give you a sense of security and confidence that few other bikes can match, as well as much less maintenance needs.
Good luck
Lewis - Sheffield