Clipless Pedals - Big Buck Benefit For Social/Commuter Rider?

[cosmicbike]

Been of to the physio again today, who reckons I'm good to ride the bike a bit more, albeit at home on the turbo. I have also discussed clipless pedals and he's all for it.
So, given I ride MTB, hybrid & road bikes I was kinda thinking towards a standard pedal for all 3 bikes, so got a pair of Shimano M520's and shoes for the hybrid. All OK.
Next up is the road bike (which tends to be used for longer rides), so, couple of questions:

1. Aside from the obvious fashion 'faux-pas' of riding a road bike with MTB pedals, will there be any real benefit to using SPD-SL on the road bike instead?
2. Other than weight, is there any realistic benefit in spending more money on the higher range pedals (eg M540's, or SPD-SL 105's etc)?

Ta

 

[Dusty Bin]

No and no. In that order.

 

[CRVFR]

IMHO the M520 is a great all-round pedal - use them on both my MTB & road bike.

 

[andrew_s]

The bigger cleat of a road pedal gives a slightly more stable foot position; with small SPD cleats you can get a bit of left/right roll, especially once your shoe starts to get worn. This roll can be limited to some extent by using a pedal with better shoe support (eg M424, M530). Plastic road cleats aren't all that long lasting, and you can't walk normally.
I value being able to walk, so I use M530 on my road bike. (M545 & T780 on other bikes)

More expensive pedals officially have better bearings as well as being lighter, but the bearings on lower range pedals last perfectly well, so the most significant difference is that top end pedals cost more to replace if you break them.

 

[cosmicbike]

Thanks folks. Quite like to look of the 530's, so may well give them a go once I'm back out on the open road, maybe the new year if I'm good...