Precisely - for a "normal" load on the Cardinal, it works just fine. Having something work less than smoothly when overcrowded will happen to any car, restaurant or burrito cart.
Well, I was on a 'normal' load last week, so the diner-lite was never crowded. But after being on 4 different Superliners just before my Cardinal trip (3 had regular diners/PPC and one had a CCC) AND having a Horizon diner on the Crescent after that, I can say that the Diner-Lites are not up to par with the others.
Of course this is just my opinion, but the quality of the food (especially for breakfast and lunch) was not nearly as good as on any of the other diners. The breakfast was especially poor. The lunch was tolerable, but again, not as good as lunch on the other trains. Dinner was the only meal that approached the quality. I had the steak, which was the roast that replaced the flat iron steak over the winter. With the sauce, it was as good as I had rememebred it to be. However, the veggies that came with it were horrendous.
The diner-lites also have a much smaller selection for each meal.
IMHO, the diner-lites just don't stack up to the other diners in the fleet.