I ride Compact frames and a sloping top tube frame. The smaller triangle is supposed to impart a better pedal response to the rear wheel, make for a more responsive bike and make for more road feel to get back to the rider. Don't know if it does- but as a short legged rider- I find I can get a better fit on either frame than the other one. There is no difference to me on feel- response or transmission of road shock back to the rider. I ride a 46.5 compact frame and a 51 sloping tube. Top tube is 1/4" difference between the two, I can get the same saddle and bar height on the two and they don't feel any different to sit on.

What I have noticed though is that I never bounce my knees off the top tube on the compact- which I do on the sloping tube occasionally. Only happens on corners and where I try to correct steering in the corners- but it has happened. Side whack on the joint as I try to change weight and position.

To me- the look of a compact is natural. It seems right and if I were asked the difference between the two- I don't think I could find one. Now as to the frames where the top tube slopes down at the front- weird!!!