Hi Martin,
Good to see you here again!
There are benefits to taking the bike you're most familiar with, and of course as we all know, the 1400GTR is the better bike.
That said, it's also great to see what all the fuss is about with regards to the other bikes. Saying a bike scares you is, in my opinion, not a good enough reason to over look it. After all, can you honestly say the 1400GTR didn't scare you a little before you got used to it?
All of those bikes are very capable, so it's really up to the rider to keep them under control. I'm sure that after a few miles, and some twisties on the way there, you'll be riding any of them like a pro.
Instead of discounting a test ride based solely on your perception of the bike without first hand riding knowledge of it, I would base the decision on expected comfort level vs. the length of the trip, road conditions you're likely to encounter vs. which bike would best be suited for those conditions, and of course, how likely will it be to get a second chance to ride those bikes in the near future.
I know full well you can encounter snow in the Alps clear into July, so ABS and/or Traction control would be a nice to have. Not sure if any of those are equipped or not.
Personally, I would love to test drive the S1000RR, but I don't think it would be comfortable for me for an all day ride.
Hope this helps, but regardless, let us know what you choose, and tell us all about the ride.
Enjoy, and ride safe!