You're absolutely right and I did - however I think they are a shy bunch, I couldn't even credit them by name in my acknowledgements

Maybe you tried already but wouldn't it — by absence of this volunteer here — make sense to ask your focus group members for this?

"Good web and social presence" rules me out. Good luck on the book, though - what's the title so I can look out for it?

…implying, you’re paying the PHP core team to use their FOSS. 

Sometimes in life people do things not only for financial benefit.

Fancy writing the Foreword to my soon to be release book?