Many moons ago I made a 50/50 Chardonnay/Seyval blend. It was pretty good, but not great.To add to blend stories. Last year we were bench testing Foch to blend with Chambourcin. Our testers guessed we would like the 50/50 blend best but it was the bottom of the list.
This week we did a quick bench test of two Chelois batches. Again the 50/50 blend was not the best.
Assuming may end up with something unpleasant and certainly is not the best method for blending.
A couple of years ago during a Finger Lakes tour, I tasted four different Chardonnay/Seyval blends. Each was 60/40 or 40/60. One or the other had to be a higher proportion, and both combinations worked. These were at 4 different wineries.
I have 2 carboys each Chardonnel and Vidal. In the spring when we bottle, I'm going to bench test a few blends. It may turn out that we bottle just varietals, but it will be a fun experiment.