Someone PM'd me how the system sounds and how the install went so I will also put the answer here in case anyone has similar questions.
I just had it installed yesterday.
For comparison purposes...I have a JL amp and 10" JL sub (powers subwoofer only) in my car, stock speakers and head unit. I have 2 10" Polk Mobile Monitor subs and Rockford Fosgate amp (for subwoofers only) in my Dodge truck, replacement head unit and replacement (non-amplified) front speakers.
For the F350 I used the JL 700/5 amp, which powers the sub and all factory speakers. The factory speakers sound much better and much clearer with the JL amplification, I'm very happy with that.
The pioneer subwoofer is nowhere near the bass clarity or loudness that I get in either my car or truck. I don't know if it is the brand, the slim mount design, the fact the box is ported, or what. Having said that, it is certainly adequate and adds considerably to the sound experience. With my other vehicles I could vibrate the whole truck, making the mirrors almost unusable. But in those vehicles the overall sound quality and clarity is nowhere near the Ford now. So a tradeoff and I think the Ford is more enjoyable so far (first impression after 1 day).
The install had some problems (I bought everything online but used the local Best Buy). After everything was installed, and I went to get the truck, there was a hiss in the speakers with the engine off. Turns out the 2011 with nav has 2 external amps - one for the Ford subwoofer and one for the 4 cab speakers which the installer didn't know about. After we figured out the problem we rewired to bypass the front amp and it was fixed.
It is important to follow the directions on the LC6i (and I assume 8i) - turn the volume up 3/4s, adjust gain on LC6i as high as possible until max light flickers, and zero out the gain on the amp. If you crank up the amp gain the speakers hissed on mine too. After doing all that everything worked.
The problem I still have is a "thump" about 10 seconds after the stereo is turned off or truck turned off. After spending some time researching, I believe this is due to the amp powering down after the other units - it needs to be off first, then head unit and LC6i. I haven't found an easy solution yet - it looks like I can use relays between the amp and speakers but there has to be an easier way (probably a dip switch in the audiocontrol unit or JL unit?) and I plan to ask a few other installers before putting in relays. If anyone has solved this problem please post it!
After looking into the LC6i vs 8i - I don't think you need the 8i if you are using the factory speaker locations - you would need to be using more/different speaker locations (I think) to need the 8i.
The spl2k box was fine - you don't see it when installed or anything so fit and finish (which looked good) really doesn't matter. It arrived quickly and all that, but I don't know first hand that it is superior to any other box for that truck. Michael did say the JL sub would sound a little better in the truck than the Pioneer, but probably not worth the large $$ difference. (As I listen mostly to country music I don't have a need to vibrate the mirrors anyway.)
I'm an electrical engineer but not particularly handy. After helping troubleshoot the hiss with the installer and tracing the wires, examining the complexity of the wiring harnesses, etc I would strongly recommend getting an installer to do it unless you are very comfortable with reading tech manuals and have a lot of time. The installers have the right tools, connectors, and experience in removing the dash/floor panels, rear seat, etc. My install was $380 and given the cost of all the components I figured it was money well spent. Plus they warranty the work and will fix it anytime it breaks, which is peace of mind for me.