I'm upgrading to a touchscreen HU and am stuck between alpine's IVA-W505, which i've heard is possibly the best out right now, and pioneer's AVH-P4100. is there really a big difference?

Ipod performance is my top priority along with overall screen quality (not just watching DVDs). I've read a load of reviews but I was hoping to get someone who has used both units and hopefully get a solid opinion.

thanks