[folivier]

It's always in your best interest to use an independent inspector and not rely on the sales organization. There are a few places that might be trustworthy but they are few.
If you'd like to post where the coach is located there may be a guru nearby that could look at it for you. Not a full inspection but mostly an experienced eye, also the year would help since they range from simple systems up to very complex in the later years. You could also ask Newell if they have someone they recommend. It's important to find someone experienced and knowledgeable about Newells since they do have many unique systems.
Paying for an inspection might seem expensive but could save you from expensive repairs while you own it. Engines, transmissions, slide bladders, air bags, generator, appliances, can all be costly to repair or replace.
One other question: do you plan to do your own work on the coach or have a shop do it?
I'm sure you've heard this if you've spent time on the forum: condition is everything.