Planning a stereo system for when my Nismo shows up

Naenyn

So I have a bit of previous experience with Apline HUs and JL Audio speakers and was looking to plan out a new stereo system for my 370Z once it arrives in November.

I'm looking at these components:
Alpine IVE-W535HD 2-DIN HU - Alpine Electronics of America, Inc.
2 pair of JL Audio C5-650 - C5-650 - Car Audio - Evolution® - C5 - Component Systems - JL Audio
1 JL Audio HD600/4 - HD600/4 - Car Audio - Amplifiers - HD - JL Audio
1 JL Audio HD750/1 - HD750/1 - Car Audio - Amplifiers - HD - JL Audio
1 JL Audio Stealthbox - Car Audio - Stealthbox® - Nissan - 370Z

At this point, I'm looking to have Sound Xpression do the install. Sound Xpression Car Audio & Mobile Video BigAudioFanat(ic) has mentioned he'd be willing to do the install too if enough people in the area were interested in having him come to Phoenix to do installs for them.

Any thoughts or suggestions? I was also pondering a box from Custom Sub Enclosure | Affordable Sub Box or having Sound Xpression fab a custom one. The later option would add considerably more to the cost of the system but would likely be the best-looking of the bunch (at least, according to the owner of the audio shop). Also, the audio shop guy mentioned that a cheaper speaker option (perhaps the C3 instead of the C5) would still sound good in the rear and would cut cost a bit. Lastly, is it really worth doing two separate amps vs one larger amp? I am going more for sound quality than loudness, so would one larger amp be sufficient?

Also, it would appear that Alpine isn't yet shipping the IVE-W535HD. Does anyone know if it is likely to be available by November?

Thanks in advance for the help!