It caters for all dogs and is not specific for seniors
There are different thoughts on this - some believe in life stage food to meet what is supposed to be different nutritional needs and others feel it is unnecessary. I am not sure, but I think that the analysis of Gentle, being mid range makes it suitable for all life stages. However, it is their opinion and I respect that. Like so much to do with dog food, at the end of the day it is down to individual choice.
The feeding guide was I think they thought "too vague"
I've not found that to be the case simply because I have never come across a feeding guide that was anywhere near accurate anyway. On the contrary, I find it easy to work out and the website does say that you need to move it up or down depending on the dog's needs. That seems sensible.
The idea that the analysis was not dry matter.
Earlier I mentioned this and suggested that you take the dry matter analysis from the Dog Food Directory of this website - it is provided graphically in the form of the dials.
Overall they said it was not good quality and they could not "put their name to it".
The review on this website does not tally with theirs so you just have to read up and form your own opinion.
On the subject of Royal Canin, it seems to take a lot of flak but tbh I have fed their products in the past and I don't remember having any problems with it. I have posted on the thread here
about veterinary advice. All I can say is that this is their opinion so you have to do the homework and make that decision yourself.
One thing I have learned over the many years of dog ownership is that there are many different views and ways of feeding our furry friends. No one thing is right and that is why I am always wary of people who are dogmatic (no pun intended) on the subject. If you feel that this product might be helpful then yes, have a chat with Beate Rothon about it and see what she thinks. You can but try it and monitor your dog's condition. I would be interested in hearing the outcome and following your dog's progress.