Well, on the input side, over-A isn't particularly a problem, as the Victron MPPTs are self-limiting on input current; it'll just clip whatever excess there is and shed it as heat. It's over-V that you need to worry about on the input side, as they're not V limiting and they're sensitive as hell... go over the input voltage limit by even a couple of V and you can fry the controller. It looks like the Renogy 100w panels have a VOC of 22.5V (though of course that's an unreliable spec since Renogy rarely knows the true specs of what they're selling) so three of those in series would be ~67.5VOC... and remember you could easily spike above that on a cold CO morning, so you're definitely running the risk of controller damage if you put them in series.
If it was me, I'd suggest either keeping them in parallel, letting the controller clip the couple extra amps from time to time when it needs to, or get a 4th 100w panel and run a 2s2p configuration: 2 parallel strings of 2 panels in series. That way your V input stays around ~45v, well within controller specs even on a cold morning, and your A input is around ~10-12A depending on conditions... best of both worlds there.
Now, sure, that 400w of panel is way more than the controller can process under ideal conditions, but it'll serve you well in the winter months when you're only getting ~50w or so out of each panel, and in the summer the controller will just clip out whatever it can't handle.