Hi. Not sure how much this costs but DH's aunt had this done at a Harley Street clinic as she was not suitable for laser. To cut a long story short, first eye was fine second has taken a year to sort out and several operations. She has since said that she would not have bothered going through this if she had known what it was going to be like.
Yes, it's because they're positive rather than negative. They only do up to a 6 in +ve for non-specialist lenses. He tried using a +5.75 and a +6 and it just wasn't quite good enough.
I guess we'll keep trying to gather information on it!
DH rides a motorbike and plays a few sports and glasses are just such a faff (not to mention expensive when they break). Also because his prescription is so strong, even with extra thin lenses his glasses weigh a tonne and cause him a lot of discomfort.