Smith I/O and I/Os is getting a major redisign so I would wait till next year to purchase them. The Oakley Air Brake really took the ease of changing lens to a whole new level. A polarized goggle lens would be more useful out west where the sun shines often vs here in the east. Taking into account that both come with 2 lens the price is really not that outrageous.
Personally I have no interest in changing lens while on the chairlift or anywhere else. Give me goggles with a Scott Illuminator, a Smith Sensor Mirror or Oakley Persimmon, I'm good to go for any lighting conditions.
Most already know this but most goggles for the last 2/3 years have an anti-fog treatment on the inside of the lens put on by the manufacturer. Very sensitive, do not wipe when wet, wipe carefully. Oakley has a little red card in the box explaining this, Smith has it on the bag tag.