Hi QP1:
Your photo depicts two guitarists. Are your friends guitar or stringed instrument players? There is a bit of a negative factor about keyboards in today's music world. As a songwriter, I would not be able to make much progress without my 910. I can select the style, instruments to be incorporated, tempo, multi-pads to enhance a melody and do so many things a writer with only a single instrument cannot do.
I would jump at the chance to own a Tyros or a 950 but realistically, cost is a factor because coming from a corporate background, a cost analysis makes it difficult for me to justify expenditures until I "hit the big time!"... LOL!
You did not mention what (if any) keyboard you own? Seeing and being able to play an Arranger (no matter what make or model) is a fairly straightforward demonstration... and the versatility of these computer based instruments is marvelous.
If an Arranger is not available for them (your friends) to see and touch, get them to visit YouTube and see what real talented players are doing with Arrangers.
Best of luck with convincing them to "take the plunge."
Dave Rice
http://www.ShowCaseYourMusic.com/DaveRice/