I've had both RT & GSA (current) and have toured Europe two up on both; to be honest there both fantastic for the job and i enjoyed each of them, i guess in different ways but it's all about the travelling. Hopefully the following will offer some help but obviously its very personal to each and every one of us and is only my view on the bikes:
I'ts funny but the pros for the RT are also the cons; the big plus on the RT would have to be seen as the fairing which is superb and keeps you dry and comfortable on a long trip in particular in the rain and with the right replacement screen (cee baileys in my instance) i could achieve such quietness that i could listen to radio 4 talking at about 80mph on the bikes speakers!! Having talked of perfection now comes the cons side; in particular travelling in southern Europe the fantastic fairing suddenly becomes a bit of a drag mainly down to heat - obviously its designed to keep airflow off you which i found included much needed cool air (boy can it get hot)
The GSA in turn doesn't have a fairing but the design is very clever in that the screen configuration (no need for alternative on this for me) and side tanks act very similar to having a fairing, not to the same degree as the RT but actually enough to keep a lot of the rain off. However this ensures that when in very hot conditions i found that you do get better air flow which for me was very good; i guess its all about comprimise.
The other differences are probably obvious but i'll comment anyhow; the RT is quieter and for me felt a bit smoother, and the GSA feels a bit more like a snorting bull that you do have control of but always feels like its alive and 'snorting' (actually i love this bit about the bike as it feels alive - the RT is so competent and smooth but lacks that aliveness)
One of the big differences i found is the GSA is much more manouevrable in the handling and in particular through the tighter bends; looking back on the RT it felt heavier on the front end and i tend to ride quicker (but not as quick as some) with the GSA than the RT.
From a two up point of view i didn't find much difference with passanger on either bike; both took it in their stride. My wife bizzarley finds the GSA rear seat more comfortable than the RT and i think it comes down to the width of seat (and no she's not a big wide girl!!) and the secure feeling she gets with the ali panniers and top box - it just feels so solid.
We find the carrying capability of the GSA far better than the RT; the RT large top case being good capacity but overhangs back end a bit too much, in particular if loaded, without having some effect. The ai panniers hold much more for the two up or solo camping and have little or no effect on the bike; also i find it easier strapping stuff on the GSA - it just seems to act like a big flatback lorry when you want or need to load it.
With the GSA i also find that when visiting the 'castle' down the rough track is something you don't need to think twice about unlike the RT which you have to make a judgemment.
I'm going to stop now as the more i type the more likely i'll want to keep my GSA and lack of work prospect tells me otherwise; in fact i've managed to depress myself at the thought of it going
Anyhow both bike are great in differing ways; you will be happy whichever you go for and i can only sum it up as follows:
The RT is like that uncle who was smooth sophisticated had a good job nice wife etc etc and the GSA was like the uncle who was a bit of a lad, lived a on the edge, liked the ladies, was funny, had a cool motorbike and although your parents dissaproved off it
'You wanted to be just like him when you grew up'
Enjoy the decision making; all part of the fun
