I could be wrong and will happily stand corrected but I do not think Orbea advertise mudguard mounts on their Gain (M series) carbon frames, only on their (D and F series) alloy frames. They definitely have them on my D30, although I do not make use of them.
I certainly agree with G3CWI in that it is more fun to ride, especially on hillier rides. And it does make you more willing to tackle hilly rides. My personal experiences are somewhat similar but, at the same time, a little different (if that makes any sense). I have found my technique on hills really effects how well the bike delivers its power, and as my technique is far from good I also experience varying performances in power delivery. However, I am certain that this is down to me as a poor rider because when I really focus on a good, smooth spinning technique the performance is pretty consistent. If I try and grind a big gear up the hills, or my spinning is far from smooth, then the performance from the bike is very varied. My biggest grip however, and it is nothing to do with the bike but more to do with my cycling ability and the limiting of speed to 15.5mph, is that as soon as my mates travel over over 16 mph on flat or slightly uphill terrain I struggle to stay anywhere near them and fall further and further back until we reach the next hill. I would be keen to try the US version with the higher speed restriction.