Agreed with SL Viper. Love the Gen V but didn't want to wait any longer, plus couldn't validate spending that much money on a new Viper. Got an awesome deal on my 2008 back in August 2012 and it was almost new with just under 1,900 miles on the clock! It was also 1 of 9 verts ever produced in this color combo (GTS Blue with Silver Stripes) so I swiped it up knowing it was incredibly rare in one of the best color combos ever and was guaranteed to be a future classic. The Gen IV is an instant classic as it is the LAST of the Supercars or regular cars that has no driver aids, and is truly the modern day version of the Shelby Cobra. As much as I love and want a Gen V, you can't say that about them as they are now chock full of driver nannies, but it is more of a GT car than the Gen IV with its luxury features and refinements. While I wouldn't mind some of those features, I also love the brute rawness of my Viper.
Soooooooo, what's the take home? It's completely your choice, but I will tell you that I couldn't love my Gen IV vert any more than I do, and just thinking about the fact that I own my dream car puts a smile on my face. Is the Gen V worth 2-3 times what I paid for my Gen IV? I'll tell you after I drive one, but I can't imagine a much bigger smile on my face than the one that is sitting there right now.
Good luck with your search and let us know what you get (and send pics!!!!)