Single multichannel amp or two amps?

Hey everyone, I am struggling with a decision as I complete my system. I've been planning my system to use two separate amps, a 4 channel 100 Watt rms amp for my main speakers, and a 400 watt mono amp for my Perfect sub. After looking at the extra hardware, wiring, etc, I have begun to think that a multi channel amp would be an easier and cheaper choice from an installation perspective. 

I would like some opinions on which approach would be best and why. I don't want to compromise sound quality for ease of install, but would also like to keep things uncomplicated if I can. This is going into a 2003 Explorer, so I have plenty of space for multiple amps if I need to go that route.

What are the pro's and con's of each setup?

I would recommend doing two different amps.  If you want an easy install, just do one run of thick gauge cable to a distrobution block, then branch off two smaller guage cables to the amps.  The install doesn't take much longer and it isn't too much more costly either.  Also, think further down the road...

-The multi channel amp dies (you now need to replace with another multi channel amp)

-You want to upgrade your subs (the multi channel may not have enough power, so you need a dedicated or larger multi channel).

When it comes to system expansion as well as possible problems down the road, it is much easier to have two different amps and just replace what needs to be replaced.  In the long run, it will be more cost effective.