I think combo tees are a very good idea if done thoughtfully. Our course, which is not very long from the back tees at altitude, nevertheless has a few holes with either daunting carries off the tee or challenging length for most players. So the combo tees, which we’ve had for about 3-4 years, and of which there are four (one on front 9/three on back 9), address that. For example, the 18th hole is a 480 yard par 4 from the back tee and 430 yards from the regular tee. From the back tee, I can’t reach the fairway bunker (which is a true hole-killing hazard), but I can definitely reach the bunker from the regular tee. So the tee shot from the regular/combo tee is much more interesting (and more challenging) to me than the tee shot from the back tee.
I play one of the three sets of tees (back/regular/combo) depending on the day and the group. The combo tees add variety and add to the enjoyment of the game, which is what it’s all about, right? PS, some of you young bombers also will come to appreciate combo tees as a nice transition from the back tees to the front tees when you encounter the inevitable passiage of time.