Well I should have provided more details in the begining, but I'm greatful for the response thus far.
Its a 95 Passat, ODB1. So only 1 O2 sensor. I don't have a CEL on. I'm averaging 450 km's per tank of gas (remeber thats 70 liters in a Passat, not 50 like in G/J's). I'm using 93 octane from Esso or GTO. My MFA tells me an agverage of 12.5 - 13 l/100 km's but if you work out the milage for 450 km's on 70 liters (I worked it with 65 liters actually because it wasn't right on empty - and no gas light on B4's) you get 14.4 l/100 km's. Yuck BTW, this is mostly non spirited city driving. I have like a 10 minute drive to work down a single street. Traffic isn't really stop and go. Just a few lights.
So getting back to the original question, are there noticeable driving differences between a VRsick with a bad O2 and one with a good O2. Like I said, if this were a 16v, you'd be hesitating when giving gas under load, and the motor would drink more too. But the 16v isn't efi, its CIS and therefore a lot more sensitive to improper fueling.
Last night I ordered an OEM O2 sensor anyway. For the $130 CND it cost me, it isn't worth fretting over. But for the sake of discussion, I will keep this thread alive and post back my findings when I change the O2. From reading these forums, I'm getting to see how the VR6 is more along the lines of a performance motor and so if one component isn't working quite right the whole kit goes to the crapper.