If you are buying the headunit for GPS functions get something (Kenoowod?) that has a Garmin based unit.
But keep in mind you will pay more to have it in the dash then a good easy to use and update (you all do update your GPS units at least a few times a years dont you?) that can be replaced by its self anytime without replacing the whole dash unit. I am not saying do not get in dash GPS just know it does have limitations.
Here are some things to think about besides the ratings.
Not all Bluetooth is created equal.
Knobs vs touch screen.
Size and placemernt of buttons.
Satilite Radio features if needed.
Placement of USB, Memory Card and /or aux input
The Econoline van radio mounting position while it seems good is not really all that close to reach to or easy to see while driving. The major buttons and knobs really need to be on the left side not the bottom. It also is not that good to see for GPS use or movies (especially the passenger because of the angle towards the driver, parked of course) Touch screen only controls do make the screen size bigger but can be a pain. ALL of these newer micro processor units take time to boot up some are just much longer than others. There are a lot of comparison tests about this on the web. If you like to just jump in and throw it into revese and want a camera you should check the boot times. I always back in so I dont need it to be on the instant I start the van. On my Pioneer it has a very annoying feature because of boot time. If you were cranking the tunes when you park it, when you start it you have to wait to turn it down or shut it off. The sound works right away as soon as you hit the key but the volume control even though mine has a manual button does not work until it fully boots. The stupid off button is touch screen and floats so it is not always in the same spot on the sceen and sometimes you have to scroll to find it, really how stupid is this?
I would not worry about the unit working with an iProduct if they change the connector. If and when Apple or anyone else changes something like that all of the major companies will offer a new cable as soon as they can. Unless you are one of those people who stands in line on day one of its release just to say you have one of the first million iThings sold you will not need the cable before its available. If you are a big iUser a few of the bigger car audio companies offer units that are AM/FM and iDevice only. It uses the phone for everything else including GPS. They have no CD/DVD players so they cost less.
If you are an Android user despite not saying so most units work just find with an Android phone.
If you think you will use a USB stick for music a front mounted USB port is nice to have. I like full size SD cards but my unit is microSD and they are really really small for my big old fingers. Make sure you try to future proof your unit as much as possible. If you think you might want a DVD monitor in the van (passenger side sun visor or in the back) make sure it has outputs you might want. Some units can play a DVD (and head phones) in one zone while you rock out to the radio, XM or memory card while driving at the same time. If you want satilite radio XM/Sirius make sure it can control it from the radio so you dont have to use another device. XM and Sirius are all but the same these days but XM still has better reception every time for some reason. Some headunits only have XM and some only Sirius but some have both available.
Bluetooth...Bluetooth is a must have in my book but I have been using it for over ten years now. Some units are really easy to use and pair other might have Bluetooth but its not so great. Some units cannot do Bluetooth streaming (some iThingies do not have stereo Bluetooth for some reason) for music and such. If Bluetooth is important be sure the unit can do what you want it to do.
The one last thing I will strongly recomend when installing a double din headunit into a dash designed for a din and a half radio is mounting kits. I like things a certain way, some people call it fussy some anal either way its how I am. I like aftermarket car audio stuff but it has to look like it belongs there for me. They are three or four installation kits that work with Ford vans. Some are major surgery inside the dash and other only need a bit of trimming to the trim panel. (making it difficult to reinstall the factory radio by the way) I tried three different kits before I got one I liked, it does have one set back though. Once you push the radio into place the only way you can remove the unit is to take off the whole trim panel. The kit is made by American Internation (part number FMK552) and posibly some others. It has a very narrow side and top front trim plate. Two side plate and a rear holder only, just four parts total. It takes a bit of fussing around to get it perfect but it works really good and the radio fits in the dash like it should. Here is an Amazon link to it.
http://www.amazon.com/Ford-Double-Din-D ... +radio+kit
...Jamie