I haven't had a replacement but have had hardware removal in my knee since diagnosis. The surgery itself didn't cause any issues with CRPS other than a brief flare for a week or so. It sounds like your surgeon knows a lot about CRPS so I would proceed. One surgery is better than multiple too. How old are you? Are you young enough to have to do it again later? I think knee replacements have a life span of 25ish years usually which is why I've avoided one so far. But I had a tibial osteotomy to avoid it which has a worse recovery than a replacement and caused my crps.