That was interesting Les. I hadn't heard that Canon had provided its noise algorithm to Adobe. Not sure when that dates back to or whether Canon continues to provide updates as it improves its software?
However, it seems there is more to controlling noise than that, as Ian Wilson indicated a couple of posts earlier. The article Ian refers to in the Feb 2016 newsletter measured the noise difference between ACR and Canon DPP software. I contributed to the article with measurements from my old 700D (that I've since replaced). Tests on different Canon DSLRs indicate typically a 2 fold difference in final noise levels for the cameras tested. It may not be true for other cameras. A lot of the time it won't matter much, especially if the staring image isn't very noisy and/or a fair amount of size reduction is done to an image before its used (this will drop the noise levels as you know). For those situations where the best noise performance is required (high ISO shots, large format images etc), it will make a noticeable difference to use Canon DPP over ACR - at least for those Canons tested and reported by Ian. Of course, both Canon and Adobe can update their software in the future so this pattern may not always hold.
For me, I decided not to use a workflow solely around Adobe ACR and Photoshop. Instead, I went with a hybrid starting with Canon DPP and finishing with Adobe Photoshop Elements - which is an excellent product in my view. It means I don't have to think whether I put an image through a special workflow if I'm particularly worried about noise. Life is simpler that way.