Still remains of this idea of performance is the bigger priority now above proper crewing arrangements that are safer, whether it's your opinion, the DfT, Firsts or my next door neighbours cat opinion.. ..
I'm fully aware of how trains run but then again I drive both non DOO and DOO trains so what do I know about rostering and disruption

Like I mentioned before, if trains are getting cancelled regularly for a lack of guard then it means that the TOC itself are lacking resources either not filling vacancies, over reliance on overtime/goodwill or the diagramming for traincrew is too tight with no contingency for disrupted services. This is a TOC problem, there is no need to try and dress this up that this DCO will come in and save the day. If anything DCO creates more of a problem as non DOO drivers have to be trained and have conditions renegotiated. With ASLEF already committing to no more DOO then I think this problem has more or less solved itself.
If I paid £150 a month for my season ticket, I'd want the same level of staffing on my train, if not more. FGW say that the train will DOO during disruption and there isn't a guard which is backwards. The time you do need the guards skills is during disruption, when you've stopped for a while in the middle of nowhere a guard communicating with passengers is invaluable whether it be service information or walking through with connections. DOO drivers are stuck in a cab awaiting a call from a signaller or out in the train trying to reset circuit breakers.
I await the response from the 'what's better, a train with no guard or a rail replacement bus'. My response is similar to what I wrote before, properly staff depots, have cover traincrew and create contingency plans that actually work and it's unlikely this question needs to be asked in the first place.
I'd probably go with that. I get the feeling First don't want to lose the cash cow that is FGW with FCC, Scotrail been lost with TPE possibly going as well, so will bow down to the hand that feeds and lick it clean.