After doing some research I think the best combination regulator is an Apeks dsr 1st stage with an Atomic M1 2nd stage(self adjusting) &M1 octo. On my stage bottle a Sherwood Blizzard 1st & 2nd. Any comments or suggestions would be apprieciated as I'm considering purchasing 3 sets of this combo for my sons & I.
You may be over-thinking what you perceive to be "the problem".
1. Find a regulator that breathes well for you (by actually testing it while diving), and for which service and parts are available within a reasonable driving distance from where you live.
2. Buy six of them.
By purchasing 1st and 2nd stages from different manufacturers, and putting a third manufacturer's reg on your sling bottles, you create a logistical/maintenance challenge that is entirely un-necessary.
Depending on which dealers sell/service which manufacturer's product lines in your area, you might have to take one stage of your regs to one service shop and the other stage to a different service shop.
Within certain price ranges, regs that fall into each category are difficult to distinguish from one another in blindfold tests. For example, three different regs with msrp's of >$600.00 and similar WOB values are going to perform pretty much the same. It comes down to whether you're doing the work on them yourself, and if not, who is and where are they. It's the maintenance over time that is going to be important (and costly).
So do yourself a favor. Whatever you select, just purchase six of them. Unless you're doing the maintenance on them yourself, or your local dealer sells all of the lines you need, the convoluted approach you describe above makes things way harder on yourself than it needs to be.
Besides, when you're out at some remote dive site and one of your regs craps the bed, if you have six identical regs you can jury rig another of them to do the task you need done. But if you have different 'specialty' regs that you use for one purpose or another, you lose any redundancy they might otherwise provide.
Just MHO.
Regards,
Doc