Scratch that, just got the game and played for a little over an hour, felt like how it did on the PS1 so that's a good thing for me, enjoying it quite a lot. Only gripe I have is the Wumpa Coins, can't understand how the rate of coins differ, it says in-game, coins you get depends on your position? But I've been first quite a lot and only got 40 coins 2 times while most of the time I get 20 coins, and also I don't like the always online thing especially that it's a grind for the Pit Stop unlocks.
Not so sure about this one on the boss, I've played for a little over an hour and only beaten Ripper Roo, and I've noticed he's almost always near me and only lost by 1 second, while on group race(Adventure mode) I've beaten them by around 5-6 seconds, given I've been hit a couple of times while boosting like crazy too(on both occasion).
Yeah the bosses work differently to regular ai. They seem to have some form of catchup.