I'm a novice, but I'm making the leap so that I can play with some of the other variables myself and also because it will be available.
I've made 6 kits in the last six months and started altering the kits with the third effort (changing yeasts and oak).
In the future, I really see myself doing both because of availability (year round for kits) and the challenge of working with a clean slate.
To Smurfe's point above, I think I've got a good handle on yeast, not on acids. I've also read a lot about malolactic fermentation, but I'm not certain that I can wield it as it should be and that's kind of the fun of it for me (I'll be making lots of three gallon batches with the fresh juice trying create my own little prize). That's only 36 gallons Mike, I've got 164 left for this year.
With a few tweaks, I've really seen an improvement in the quality of the final product from kits, so I see these as a great platform from which to continue to develop.
I find this little hobby a hoot because there is so much to learn and so much to enjoy too. I've always found that people in the adult beverage industry have a tendency to generally be very happy, approachable and generous with their advice and products.
All of this is gee whiz more than anything else I guess.