Piccola:
This is great to find so many experienced opinions. I'm trying to take it all in an learn in the process. I tried on some stuff at my LDS and played around in the pool for a bit. This shop sways on the side of BCD's with no weight integration, which is not bad since I have the hips for them! Seems to make my middle feel less bulky. I tried on the cumberbun style but really did not like it. I am looking at the Scubapro classic sport BCD with the attached spare regulator, and the MK17/S555. At least so far.
That rig will do you fine, and is probably close to what you learned on so you will be comfortable with it. The MK17 is a great first stage, and the S555 is a very good second stage, although not quite as adjustable as the S600 (I have both, and they both breathe similarly).
So if you're 100% satisfied and your mind is made up, go for it. If you are willing to consider more advice, however:
Back inflate is more comfortable in the water. Anyone who tells you it is a problem on the surface is clueless, but it is true that it is not as simple as a plain jacket... on the surface. Underwater, where you spend most of your time, back inflate is better for keeping you nice and horizontal, as you should be.
If you want to feel LOT less bulky, however, ask your shop about a backplate and wing setup (bp/w). It should cost similar to the BC you're looking at. Huge reduction in clutter, and the best for keeping your position in the water. Fantastic for cold water diving. Also removes some (but not all) weight from your belt.
(There's the formal bp/w recommendation people were expecting!)