Saunder's many never get his confidence back. Plant went out fighting and never lost his self belief. Boxing is 90% mental.
Saunders to both questions. Plant takes a few of the early rounds but BJS would keep the pace higher than he'd be able to last through - second half of the fight becomes an absolute clownshow. Neither had the power to keep Canelo honest and neither really has the power to keep the other honest, so it comes down to talent and ring IQ, both swinging it firmly towards a BJS decision IMHO.
Saunders, a Traveller from the UK, is a "European bum", yet you rep Tyson Fury, a Traveller from the UK...?
They're basically one and the same, Fury himself referred to them together as gypsy boys. Saunders primary shame is inactivity - too many relatively easy fights, not enough career defining ones (and even then, Lemieux is a far better win than Uzcategui)... A lot like Fury, just a level or two down, too many bums, too much inactivity, it should all sound familiar. Saunders isn't amazing, but he's still better than Plant who is also nothing amazing and less proven.
I'd like to see it, the winner gets a new lease on life and nobody is going to want to fight either of them anyway. With no belts and coming off losses they become high risk low reward. BJS has been better but Plant may still be improving and BJS is definitely heading the other direction.