Here is a view from a former Roland dealer..
When I first opened a MI store in the early 80's, I contacted and was contacted by virtually every rep in the area..
I was fortunate to be exclusive area dealers for many product lines...I was 25 miles outside of Philly and really didn't have to compete with the great Mom and Pop stores like Cintioli..In fact I had great re-pore with Cintioli, and his support for lines I did not carry...
Getting back to Roland...Roland reps were very cool guys and loyal to you as one of their dealers...I supported the whole line, including effects, keyboards, midi guitars, amps etc..
The choices of what I wanted to carry ..were my own (although I did carry all the models)...
Yamaha played games..they set ridiculous high volume orders , according to their specifications...stuff you could not give away..
Korg had a limited range of gear, and was not worth stocking a lot..
Ensonigue was popular in our area (especially Mirage)...but only a couple models..
Siel , was our surprise line...for the price the stuff sold...
Casio was the local attraction line for parents buying kids keyboards..
The cheap Yamaha keyboards did not sell well..the Casio out did them back then..
Now the facts not guessing as the previous posters opinions..
If you are a straight shooter as in honest, the Roland reps will have your back and support you...They went out of their way to make sure I got the deals as the large chain stores did...When there were special buys, they cost averaged my stock , so I would not lose on inventory..
I was giving a welcome in Namm, Dealers were all treated with respect...
I was given a protected dealership in my area, some of the other dealers tried to back door Roland products...but Roland put a stop to it immediately...
Roland sponsored clinics/shows for my store, including artist participation....
My Roland experience lasted for almost 20 years...
The Roland line is the largest across the board product line, and all top shelf products...You will not go wrong with a Roland dealership...in fact if you pass on the chance to become a Roland dealer...it will be a BIG loss for you...
As always , the key to success is your relation ship with your reps and customers...