Is there a viable space between the extremes of luddites and those who are looking forward to the future synthesis of human and machines?

I hope so. Although I would wager that entertainment will bring the two groups together. People will plug themselves in and cast aside much for the sake of being entertained.

Should one withhold ideas and inventions from public at large?

I don't think they should. I am not comfortable granting intellectual authority or technological authority any more than moral authority. No mind or group can be deserving of that trust, because there is no measure for what it would require.

(aside: throughout human history, many schools of thought sought refuge in esoterica and clothed their outward appearance in misdirecting, e.g. occult, symbolism both to (a) filter membership (as in spot the bozo) and (b) to permit a pseudo-public discourse that resisted penetration by the uninitiated.)

I believe those most interested in these groups are usually standing on the shoulders of a greater person. I also feel that intellectual cowardice and self-deception is typically involved.

Are these concerns too much to burden the creative technologists? Should we just go with the flow and trust and hope that the actors that utilize our mind-products are responsible, humane, and thoughtful?

Yes, we must go with the flow, but no, we should not trust. We should shine light on what is made, and actively debate its use and value. In short, we should put energy into the process, rather than in a grand design that will inevitably fail to match actual developments.

Those are my opinions, at any rate.