I have had a Monsoon 3.0 Bar twin in/out for about 40 years and it works brilliantly, supplying two showers at full belt with no problem. Made by Stuart Turner I think, but quite pricey now. I have the same sort of setup as you.
Regarding push fittings, I owned some small rental properties a few years ago, where, to improve water provision for bathrooms and kitchens, it was sometimes necessary to think creatively, and I found that if good quality push fittings were used correctly, it allowed me to resolve issues that were otherwise insurmountable. In a recent extension to my own house, while I always prefer to use copper pipe, again, to allow some new radiator pipes to be hidden, it was necessary to use push fit.
When installing a water softener, to provide a non-softened tap in the kitchen at the rear of the house, I also used push fit to provide a single feed from the rising main in the downstairs cloakroom of my house up inside the soil pipe trunking, via two right angles, into and across the loft, down via the airing cupboard then connecting to copper for the rest of a boxed in run with other pipes. Without the use of push fit, this would have been impossible without serious internal disruption.
I moved my son's bathroom upstairs in his terraced house, again, almost impossible without serious problems.
I mention all these jobs as I have never, touching wood, had a problem with any of the fittings.