I'm one of the people, or maybe the only one, who had their 2.8 non IS replaced with a IS II model back in April.
Here's how it went down... As a CPS member I decided I'd take advantage of the repair discount and clean and check coupons and sent in a couple things. My 70-200 f2.8 had developed a slight haze after 17 years of use in some harsh conditions...this was a lens I used shooting snowboarding for a few years so not surprised that it took more abuse than any of my current gear.
Canon gave me a reasonable quote of about $250, but said it would be a few days to get parts so since I'm a CPS member they sent me a loaner 2.8IS v1 to cover me on my shoot. A few days later they called and told me it was more damage and it would be $350, then the next day called and said it couldn't be repaired. I was told that I could get a replacement lens instead for the same cost as repair, which was fine by me. I was a little surprised though that they then sent me a 70-200 f2.8 IS II, happily surprised of course since it's a wonderful lens and one that I was hoping to buy some day after selling my repaired 2.8 nonIS.
Maybe this was a one off event, maybe this is SOP now, maybe it's just a perk of CPS and shooting Canon for 20 years, but I'm a very happy customer and will stick with Canon and CPS for the foreseeable future.