I suspect most would not even think about a managed install, but send a router, let the end user install it, maybe even on an extension, then both would wonder why they don't get the advertised speeds. After much frustration, an engineer may be sent out, and a proper filtered Master Socket would be fitted, and the end user would then need to work around how to cope with the router in the wrong place!
I do wish ISP's and even more OFCOM would spend more on education of end users, rather than stuff the spout at the moment - especialy the latest speed rubbish!