OK, so as long as you stay to a 54 frame size, the S5 head tube looks fine. This picture compares a 56cm SLC-SL to a 54cm S5. As you can see, the head tubes are comparable. Now, the larger you get than 54, the worse it looks. At 60 and up, it is simply fugly beyond belief.

Admittedly, the -17 degree stem doesn't look great, but I think I can live with it. I used the same stem, slammed on the larger SLC-SL and I need to do the same on the smaller S5 to maintain my stack and reach.