I've gone the other way, F800GS to R1100S.
Loved the 8GS for great fun, impressive power band (for an 800 twin), sweet exhaust note, on on twisty B-roads in any weather it it'll take some beating. However not great for comfort, the BMW comfort seat is an essential extra. Also I found the GS hard work on long distance, wind protection is poor and creates significantly more wind noise than any other bike I've ridden and these together made dual carriageways/motorways a toil. Build quality is significantly poorer than other BMW's that I've owned, in fact I think this has been deteriorating for a few years now, both heated grips failed on mine just outside warranty.
Can't really comment on the Tiger or the Versys, other than to say the Versys is ugly
I've test ridden the Sprint, great engine and was tempted to buy it bit the dealership was severely lacking in customer service. Also test rode an 1000SX, fast smooth but for me didn't get me pulse racing, very competent bike but I suspect I could get bored of it fairly quickly and I would imagine the same would apply to the Versys.
As for keeping your 11S & 12S, I think that's a great idea, not ridden the 12 but my 11S is my favourite bike of all time. I could be biased as I'm still in the honeymoon period (owned 7 months, ridden 6k) but for me its an enticing blend of performance and practicality and it engages me as a rider more than any other machine I've ridden.
