Like you I started out with a hybrid, Trek 7.4 FX, around 6 years ago. I loved it but started to get a bit more adventurous and felt the bike was holding me back. 2 years ago I purchased an Emonda ALR6. It was 4 ounces heavier than the SL5 carbon, had full ultegra groupset and Aeolus Comp wheels at about $1,000 less than the SL. I absolutely love it. My speed has increased about 4 MPH (but lots of that is that I'm just stronger) and I'm now riding between 45 and 55 miles on a fairly regular basis, at least once a week with a couple 10 to 15 miles rides in between. If you can afford it, buy the best bike you can but don't judge the quality only because of the price.