9 years later, but it's still a valid conversation.
As a 50 year old with a love of knives since I was a kid...I've owned a ton of knives. Everything from flea market crap to high end custom knives. And the smallest Swiss Army knife to big 'ole "survival knives" (I hate that phrase). I agree with most everyone here that for field dressing a whitetail, a 3"-4" blade is best. Heck, I've never used one, but maybe a 2" blade would be better. Why I'm chiming in is, handle size and knife weight should also be considered. A large handled knife is much easier to control for precision work as well for leverage, when you need to put some weight behind it.
On the other hand, not all knives are created equally. My Carter Cutlery Wide FS1 Outdoor Knife with its 6.18" blade is LIGHTER than an ESEE 4 with its 4" blade! Truth is, if I could only own one knife (gasp!), that's probably the one I'd keep. If you know what you're doing, you CAN choke up on it for more precision work. I'm glad I'm not forced to have only one knife though. I should mention that I only own 2 dedicated kitchen knives and 4 other knives.