Andy, I replied yesterday but there was something wrong with the forum as I did not see your post (other than the email to me) but I was able to reply which disappeared.
I was only aware of this new feature a couple of weeks ago just after I had paid for Topaz Gigapixel which does much the same. At this time you can only use the Adobe feature in PS not in LR which I an sure they will add shortly. You can use Topaz Gigapixel from LR or PS. I have read reviews and they all found Topaz to be better. I have only briefly tried Topaz and the Adobe feature so difficult to draw my onw conclusion yet. In the past I have not needed this but have recently bought a Sony ML so I may have the occasional need when heavily cropped and we resume printing.