I went through the same exact delema on my car with the 08 hood I added however there are trade offs. If you ever want your old hood back on the car, then do not blend. Otherwise plan on painting your old hood too and then just blend. You will be okay in either case, just in case.
I lucked out in that the shop that painted my 08 hood GTS Blue Metallic did a great job. In the sunlight, you can not tell the difference, but in the dark shade you can tell the metallic paint is slightly off. I did not blend into the fenders as I wanted the rest of the car to be original and be returned to original if required, but since I only drive my Viper on sunny days, nobody really gets to notice the slightly off color in the dark shade. In fact they matched it so close, that nobody else has been able to notice it is off. Of course I know it is off in certain situations, but you kind of learn to live with it.
Like others have said, it is very hard to match up without blending, but sometimes you can luck out and get close enough not to bother.
Hope that helps. The body shop choice is the hardest choice. If you were in Colorado, I could point you to the shop that did my work and all the work for the Vipers in this part of town. They are very good, but I am sure there are others in Texas just as good. If you do not blend, then as the trade off, match the color to direct sunlight and match to the front fascia NOT the fenders. With the angles on the fenders and the hood, even factory paint on a factory car can appear slightly different fender to hood when really look closely at it. If you match it to the front fascia, then you will have the best trade off when looking at all the view plane angles. That is what they did on mine and it turned out pretty good. Matching hood paint to the fenders paint angles for metallic paint colors, is the wrong move on a Viper, if you are not blending. I know it is a mouthful and probably contadictory in certian ways, but that is what they did on mine without blending and it turned out great. Anyway, good luck.