I stand by what I say. I agree, some of your business class pax might not be thrilled but if you do a straw poll of people departing on that 757/767, the majority would not really care.
As someone who has worked for a couple of 'legacies' and low cost, it is very, very rare that you get complaints about bussing provided it is handled efficiently. And trust me, the crew get all the complaints. The low cost carrier however, as a business, doesn't like bussing generally speaking which is probably why Ryanair hasn't been shipped onto a T1 stand. Plus their aircraft, in the summer at least, don't spend 3 hours on the ground.
The AA product ex MAN isn't great, that I agree in, and good luck to those who connect via LHR, I know I would if I ever fly AA-I tend to only fly them domestically. But to suggest they'd connect through LHR due to a 5 minute bussing experience at MAN is pretty ridiculous.