My hubby and I have done a couple of the Edelweiss tours, Southern Italy and Sicily one year, and Germany/Austria/Czech (Moto GP in Brno as part of the tour) as our honeymoon!
Our tour through the Austrian Alps was in August, but we had a few days of rainy/cold wet weather. This is what we took with us for gear (we both have similar gear):
Joe Rocket mesh coat with inner rain liner
textile pants
full rain suit that could fit over top of our gear (pants & coat)
one pair heavy gloves, one pair light gloves
helmet and boots
Additionally, we had multiple light layers that could be worn under the coat and pants (long-sleeved t-shirt, pullover fleece). Bike shorts were great under the riding pants, and meant when it was really hot, we could pull off the riding pants when we stopped for a break! We both found we could usually come up with a combination of layers that made for a very comfortable day! And the heated grips on the BMW's we were riding were phenomenal in the cold.
Hope you have a wonderful trip! The guides are great, and make the tours a lot of fun!
(Actually my avatar pic is from that second tour!)