Here's the only question I have on your setup Chris:
If you have a burst disk failure, tank valve o-ring failure, cheater bar failure, tank valve face o-ring extrusion, or regulator failure at 200 feet, can you safely ascend on this gear and do all your deco without running out of gas and dying?
If the answer is no, then you are cutting corners. It doesn't matter how fancy your gear is, or how much it costs. It does matter if your risk management is good, and if you have enough training and experience to plan enough contingencies to survive.
I see at least 3 ways you could kill yourself on a dive like Randall and I do with the gear you have if you had a failure. It's not new gear or good skills. That's called a false dilemma. You are essentially saying that you can either have old gear and good skills, or new gear and no skills. It's both. You want the right gear, regardless of age or cost, and enough experience and training.
It has nothing to do with your income level. It has everything to do with your safety. I had 21 minutes of deco yesterday at 20 feet in 45 degree water. Without accelerated deco it would have been 56 minutes of deco. Doing it all on air (which I wouldn't) with no trimix or EAN50, it would be 50 minutes of deco. That's in the realm of If you get a leak and you cannot isolate it, then you die. That's no bullshit.
Besides you can find an isolator manifold on Ebay for 75 bucks. Just go buy one. At some point, you are doing this on purpose just to be different, and that's totally fine. Just don't make it some sort of self righteous thing. Just be honest that you are diving without contingencies, and that if something happens you will most likely die. Acknowledge that lots of people won't dive with you that way if you put yourself into an overhead environment and rack up deco.
As long as you are intellectually honest with yourself, that's what matters.
From my perspective, I don't spend money just to spend money. I spend money on my gear because I view it as the bare minimum to make 200 foot dives with significant deco obligations, and to not risk killing myself or my buddy. I make every effort to go home to my wife alive. My dive yesterday was 82 minutes long. If I would have lost my deco gas, or my computer/backup tables, or if I would have made a mistake, I would have died. 21 minutes of omitted deco is most likely "dead before you get to the hospital" amounts of omitted deco. I bring 2 computers, 2 masks, and isolated doubles because I truly feel, after doing detailed analysis, that it's the only safe way to do dives like this.
This isn't me bullshitting on the Internet either. We see each other periodically. If you want me to show you all the failure points in this setup, I'd be happy to do so. I'm not saying this to crap on you either. You are a hard working guy, you are funny, and you are fun to have around. I just don't want you to think that this is a particularly risk averse way to dive, and also for anyone who reads this on the Internet to think that this is a risk averse thing to do.
You could do this safely with an isolator manifold, 2 quality first and second stage regulators (no matter the cost), and two sets of waterproof notes with no computers. At some point, what you are you doing is not about cost, it's a choice predicated on some sort of other thing I'm not sure I understand.
You can be thrifty and still be safe. It currently appears to me you are emphasizing cheap, but not at all emphasizing safe. You have 4 kids. Someone owes it to you to be honest with you. What you are doing, in my opinion, is not super safe.
I should also be intellectually honest and admit that I have often done air deco dives with a double hose, no BC, a wetsuit, and a single outlet manifold set of doubles. When I do those, I bring a float and hang a bottle to do my deco, just in case I have a gear failure. That way, I can buddy breathe up to the fifteen foot stop, and do my air deco the old fashioned way. I don't do 50 minute decos this way though. I do like 10 minute decos this way. That's straight out of the text book for 1965 though:
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The impossible missions are the only ones which succeed. -JYC