A question I would have is when you ran the 1/8 mile which did you use and how did it hook. Same gears you will be running this time? If nothing has changed but the tire and it hooked well I would stay with the 26" tires although I agree that slicks will hook much better. Going from a 26" to a 29" I would expect a difference thru traps of about 800-1000 RPM. This could make a difference in the power band which may effect ET. As stated above I would take both and make some trial runs. Best of luck.
Rod