I think that good fit has a lot to do with how easy or hard the adjustment is. I had a Sirrus last year. It was a little too big for me as a hybrid. Then I foolishly tried to convert it to a road bike by changing to drop bars. WAY too long a top tube for that; hurt my back climbing a hill. So be careful when you are trying to make a bike fit if it really is too big for the purpose and for you.
When I finally concluded I needed a new road bike that fit properly, I did a ton of research on bike geometry, WSD, etc., and got two bike fittings with two different people who gave me approximate measurements for what I needed. I then walked into the LBS armed with numbers, so when they said, oh, this Trek will work for you, I was able to say, no, it won't--the top tube is an inch longer than will fit me; THIS is the range of top tube length I need; please let me test-ride these bikes that I know have that size top tube. Etc.
I strongly recommend a bike fit appointment with a physical therapist who has cycling expertise. Such a person is not trying to sell you anything and can give you a good idea of what will fit you. When I did start riding my road bike, the adjustment was easy because it really fits well. I love it and am very comfortable on it.