Alpine IVA-D901 or Pioneer AVIC-N2?

hey all. i need some serious help from any of you who install, sell, or own these head two head units and know anything about them.

im looking to buy one soon, and ive narrowed it down to these two. either the alpine 901 or the pioneer avic-n2 (by the way, i know alpine isnt making the 901 anymore, or at least they took it off of their website, i guess for the new models coming out soon - but im sure i could still get this off of ebay or someplace on the internet)

anyways, i know both can be bypassed easily (ive read on this forum how to do all that), so thats good. i like how the pioneer comes with built in navigation, with alpine you have to spend the extra money on nav. also, with pioneer you get 2 discs with the entire US and Canada on it. with alpine you get 1 disc and it has like 5 states per disc. each disc you have to buy extra (i think?). also, pioneer retails for half as much as the alpine 901 + the alpine nav. i want to control my ipod from it, both have a control box that will allow that.

my question and concerns are this. i like the alpine set up because 1) the screen is super clear. 2) the disc stays in the nav, so its always ready. with the pioneer you  have to eject the disc to use the dvd player. now, i know that you can program a route, then eject the disc and it will store the route in its memory. my big question is - what if you miss a turn or take a detour after programming the route and ejecting the disc? lets say i need gas and have to exit off the highway and drive 2 miles out of the route? now, the unit will have to recalculate the route. can the unit recalculate the route without the disk in??? this is my main concern. or do i have to put the disc back in so it can pull information from it in order to recalculate?

also, give me any other pros and cons if you have owned these.

thanks guys!

The memory navigation in the pioneer stores mapping around your original route and will re-route you back to the original route if you miss a turn or stop somewhere else.  Exactly how far you can go off route depends on the map density of the area (I think they said between 3 and 12 miles off the route.)  If you are really worried about swapping the disks, Pioneer also makes seperate nav units like you mention about the alpine.  For about the same prices as the 901 and nav, you could get the 7600DVD and AVIC88DVD.  Similar price but better sound quality than the Alpine (and N2 for that matter.)  Sorry to add another option to the picture but something to consider