There was a CAT3 on our local team "back in the day" who did all of his training rides on a beat-up Trek 2200 or something like that who carried a 28 oz water bottle filled with pennies. On race days he pulled out his Trek OCLV and left the waterbottle with the pennies at home. It worked for him...

So, the moral of the story is, what ever works best for you.

Give it a go and if you and your stoker don't find yourselves biases towards the ride characteristics of one tire vs. the other, then it could be a good move. FWIW, I was never able to adjust to the "feel" of a 28mm or larger tire on our first tandem and have used 23mm or 25mm Vredestein Fortezza's exclusively ever since: 23's for smooth roads near to home and 25's for chip-seal or unknown conditions associated with travel. Of course, we don't race so that makes our requirements horses of different colors.

The performance tires don't last all that long; about 2,400 miles/ea when rotated front to back or 1,200mi for a new tire on the rear. However, I've been able to find them on sale for ~$25/ea. now and again and stock-up. I think I've got three 23's left and perhaps four 25's (special order @ $36/ea with club discount) in my tire bin.