Right now I'm using the forty-something liter top case from my Ducati Multistrada on the Zero SR, but once I sell the Ducati I will need a Monokey top case. The two contenders are the V56 Maxia and Trekker 52 (or possibly 46). I had a Maxia on my old Yamaha FZ6R but foolishly included it in the sale of the bike. Loved that thing, and for some reason it improved my gas mileage by a good 3-5 mpg for reasons I can't explain.
On the other hand, I can get a Trekker case at the dealer price, so we're talking ~$350 for a 52 liter Trekker with backrest vs almost $600 for the Maxia once I add the top rack and backrest. My theory is that the Trekker would not need the top rack because it's rectangular and I could just strap things on top without them wanting to slide off. It also seems to me that a rectangle would provide more easily usable space than the rounded shape of the Maxia.
My concern is that the boxy Trekker will have a larger aerodynamic penalty and affect the range, and also that I might have to get a 46 liter because the 52 might look too big on the bike, whereas the Maxia's sleeker appearance doesn't stand out as much even though it's huge.
Has anyone mounted a Trekker or similar top case on an S/DS-platform Zero and did you experience a range penalty or had people think it looked out of place?