@Binje, As I also own an Imago, I gave it a go with your load. It fits in the Imago, with no room or options to spare for bulkier winter gear. IMHO, the Pilot in Dyneema is the way to go even though it is 25 cu.in. smaller than an Imago, its space is better configured. I know what you mean about how large the Imago feels. It feels a lot larger to me than my Pilot, but in my case, it is primarily because the Imago I have was not offered in Dyneema, which is lighter and silkier, and more forgiving on full packing. To me, my Imago feels clunky and heavy (no boos and hisses from Imago lovers please, this is a personal preference.) With an Imago, you would also need to ask yourself whether you like flapped bags or not. As you already own messenger bags, this may not be an issue for you.
Please don't fret about the need for a Pilot over a CoPilot. At first glance you wouldn't necessarily even notice much that the bag is bigger than the CP. It "reads"about the same size. I have both bags in black dyneema/wasabi, which would account for some of my poor differentiation skills. The front pockets on the Pilot are little miracles. You will be able to fit all of your non-gym gear in the three front pockets, including an 11.5"banana, maybe even a quarter of a watermelon . You could even likely put a shoe in each pocket in the front if you so chose, giving you more flexibility in the main compartment.