I actually missed Porkchop the year he was in the vendor area.  I can't remember why, but it was unfortunate because I had already purchased an 8x10 from another vendor.  I still have it though, so I'd be all for him coming  back.
 
While I didn't miss him, I wouldn't mind seeing Mark Lewin back since I didn't get a photo op and I have at least one more item I'd like him to sign.  Even if I did briefly think I had pissed him off  
 
Being stared down by the Purple Haze (and not knowing why) is an interesting experience. I'm still not entirely sure why, but everything turned out cool.