I use Pink Iridium from Oakley as my all around. I always have my other goggles with me as well. I just keep them a locker in the lodge. If you have a backpack, just carry it there. I don't understand why your friends would only bring one lens if they have multiple ones. Defeats the purpose of having multiple lenses.
Oakley is super durable, hence the price range. I finally managed to scuff my lens on my Splices. The reason this happened? A group of us climbed up piled snow in the parking lot for a photo op with our boards. On my climb down, my board slipped and it came crashing into my goggle edge first.
Definitely scuffed. I'm sure other goggles would have been badly scratched or cracked even. Glad I was wearing my goggles. I would have had a pretty cut on my face.
On the flip side, I have a pair of 2012 Spy goggles. Don't know the name, but they are big like the EG2. Some tree riding and branch whips caused knicks all over the lens. This only further proves to me the better durability of Oakley lenses.
Plus you can find Oakley on sale for affordable prices. Why get another lens when you can just put it towards another goggle on sale?