Definitely agree with you there. The COBRA bite comes from nearly all plans requiring that you are an employee receiving wages all year to keep benefits that the level you are currently paying (since the employer is only paying the huge portion we don't see, when you are earning wages).
You might have to finagle a deal where in the Co-Op plan, you are paying a lot of the whole year's health premium up front to cover all 12 month's of the tech's contribution share. It is still overhead to the Co-Op, so there would likely need to be a provision where the tech had to commit to a minimum of "x" number of outages/year which would cover the Co-Ops overhead.
Various things would be a trade-off. In order for the Co-Op to have low overhead, there wouldnt be many recruiters or other sweet voices on the phone, so some techs might feel insufficient lovins. A baseline year-round "real" health care plan is probably feasible, at the expense of rental cars or huge bonuses going away.
Profit sharing would be great....but in the places where I have worked that had it, a significant portion of your "compensation" was at risk depending on how the company did. How many techs would do the math and realize that the $3/hr they are giving up now for profit sharing, could be 0, or $3000 at year's end?