I did this tour last June. This statement, "the guides showed real concern about our well-being, and made every effort to accommodate everyone's condition" was absolutley true for me.
I seemed to be the only person on my tour with slope and stair challenges. I can do them but I'm slow. I also take a medication that slows my heart rate and I had an awful bronchial cold on that tour.
Our guide was very good at advising me about the steps and slopes we would encounter. I recommend that you talk to yours to work out a plan for you to handle them.
Taxis were my friend. They are cheap and I used them several times. One fun thing about taxis is that you don't go the same routes as the walkers.
For me, Granada was the most challenging, but that's not the only place with slopes or stairs.
The best guides I've had were ones that took to heart the concept that if you can't carry on a conversation while you're walking, you're going too fast. The local guide in Toledo was tuned into that, as well as knowledgeable and a great teacher.
I hope all works well for you.