Hey - I appreciate your thoughts everyone!
1) I agree, if he likes it he'll ride it.
Luke was riding 2 wheeler w/o training wheels 2 weeks before his 4th bday, and you are right it's all about "being with dad".
2) Durability / lightweight of SS & ridgid fork vs 6-sp/movable frt fork.
His 16" SS ridgid frt fork is generic store model now, a tank, seemed to me the 20" Specialized we tried out was just as light if not lighter with more features.
So, it boils down to robustness of having a kid use 6-sp rr derauiler.....
3) He really like the color scheme of the Red Specialized we saw in Brighton, the Red frame definitely was cool

however the Gary Fischer I can image would also be totally ok to him

I need to take him to 14/haggerty cycle/fitness and have him try the Gary Fischer's there, check its standover fit to Lukes inseam height....then make a decision. Yes, I can comapre online but seeing is knowing truly.
I'm more and more leaning towards the 6-sp w/front shock.......
future side note:
I'll definitley help with Mountain Kids in 2-3 years.....my boys 7 and 5 I feel still "young" for organized ride events....IMO