I haven't had any experience either so googled it and got this
The success rate of TPLO surgery is extremely high, with as great as 90 percent of dogs who undergo TPLO surgery returning to normal or almost normal function. Because of the high degree of success, it has become the treatment of choice in large-breed and/or athletic dogs.
So @DonC has the right of it - talk to people with larger dogs. Not sure that I would class Poms as 'athletic' though !!!