Warm up times do not catch us out as the house has sub zoning that gives each room the chance to control its own needs - the system thinks that everywhere is UFH even if it is rads.
How about this system:
View attachment 110184
Picture taken while in progress, 236 square metres of UFH with a couple of rads.
All working perfectly.... Customer is a regular whom we install several complete system a year for - nearly all UFH - in fact the job I am starting next week for him is 50/50 UFH and rads. All to be run from those pump stations with no local temperature control at the manifolds, btu each room zoned accordingly.
Last year we signed off another for this customer 8Km of UFH in one house. All happy as Larry.
YOUR small circle of chums may not have good experience, but that does not mean everyone does. And to assume an installation is going to be poor - as in implied by your and Bernard (who repeatedly proven to be ignorant of system design considerations and should be banned from the plumbing forum) detracts from the, no doubt, millions of miles of tube that is installed around the globe.