i've never squatted on a 'standard bar' so I really don't know.. I'd imagine weight would 'feel' heavier/less stable on a standard bar, because of how small it is and how the ends don't usually rotate.. not sure though, never had a standard bar in any gym i've been in.
The guys here are pussys , most gyms don't even have a squat rack and this one that im going and has a squat rack uses normal bars , not only for squats , everywhere , bleh!
Previous gym had nice oly bars ( even the small EZ bar had thick rotating ends ) but no squat rack , meh...
There's a new gym opening near my home and it looks like a good one, lets see...
Squatting on a smith would definitely suck compared to oly bar though.. Trying to go deep on a smith would feel like hell I imagine.. I personally would think it would be 'harder' on a smith to go deep than free bar, just because of how locked into position you are with the smith, for me i'd hate that.
peace
For me it's easier to go deeper at the smith , but it leaves a fake feeling , the forced vertical descend and the assisted balance make you feel it's an artificial movement , squating at the smith machine is horrible!
Even with standard bars free squats >>>> oly bar smith squats.