"For full specs and comparisons, check out the complete 
    comparison chart. We’ll begin shipping out pre-orders for 
    the Myo Developer Kits next month, with final Myo units 
    shipping this September. All pre-order units will have 
    final hardware."

So if I understand this right, there is absolutely no difference between the hardware you ship to developers soon and the hardware you're shipping to end users in september? If so, what is the qualitative difference between the dev kit and the final design? Just the software and documentation?

I personally want the dev kit, but if the only difference is about a month or two of wait time, I'd rather wait for better, more refined hardware.