Sounds like a painful contrast in service levels, Jonathan1974.
I had some very ropey MF service when they had just started out, which shouldn't have happened - I think it is pretty widely accepted that the first set of MF staff didn't get enough training and support on how to do the job consistently and efficiently, but only on how to do the job, leading to a lot of service inconsistency or slowness. So BA threw them in at the deep end and it showed.
More recently (over the last year or so) I have found MF service to be often very good, still variable but much improved. Variable service quality is a chronic BA problem, unfortunately - I've had a couple of right grumpy sods on MF routes and on WW routes.
I think that MF are now as good as any other BA crew, I really can't tell the difference just from service quality any more.
I can't remember the complexities of the hats any more and the rule of thumb that MF all look young isn't true either, plenty join BA after varied careers in other jobs, so these days I really can't tell them apart well. Unless the Cabin Service whichever shows up or I hear a PA with the title, then I can work it out from the Director or Manager.