Been playing a bit of Rory lately, and I really like the challenge of putting. I never feel cheated.
If I was playing with a group of guys that all used diagonal swing, then I would use it to play with them.
Honestly, it adds difficulty I'm not interested in. I play with the hardest settings in everything else, but I don't want to try to hit diagonal. On top of it being really hard for me to get down (I suck at aiming in shooters, too), As long as I'm having to calculate club and power, and still adjust fade and draw and such, I'm okay skipping that part.
I play around par at best. The main thing for me is taking out the zoom to aim. If I start beating the pros in my career, then I might go with diagonal swings.
But if there is a country club, and those are the settings, I also don't mind losing if I'm playing on all the same settings. i just keep practicing. But if I'm competing with myself in a solo mode, I won't use it.