One thing that surprised them was the height of the toilet. It is plainly too tall for both of them. They have a question to ask the factory about a lower pedistal....maybe no pedistal.
I do not know about the toilets in the newer models of the 2350 but from the pictures it looks like it is on a pedistal. But in the 2551, the toilet is much lower since it is a different model toilet and it does not sit on a pedistal. Having had both the 2350 and now 2551 it was a real surprise when I first used the 2551 after having been used to the 2350.
They liked our older sliding windows for improved air circulation while parked.
At first we were not sure if the newer style windows would give us the air circulation but having had both kinds of windows now we find the newer style to work very nice. Surprisingly you get very good circulation through them. And the best part is you do not have to worry about them being open if it is raining. We also like the rimless look on the outside.
It may be the old uncomfortable jack-knife style sofa.
When someone needed to sleep in our 2350 on the sofa I always placed a piece of memory foam underneath the sheets and there were never any complaints. I would then roll the memory foam up and store it behind the sofa.
It is nice that they had a chance to see your unit so they can now compare the differences between 2007 and 2013. Hopefully they will be able to pick and chose and get exactly what they want.