the review for the Maestro that someone posted was great.. it doesn't make a good booster, but for the price, you could follow it up with a Turbobooster and end up spending the same for both seats as you did on the Nautilus (give or take... depending on sale prices and such)
I would definitely try the seatbelt... I know with the Bolero (I'm so cheap, I know, but I just didn't need that extra butt pad or recline bar for a spare seat, which is now my niece's daughter's main seat... she was already ff, so I figured passing it on to her at least ensured her daughter would continue to be properly secured when her scenera I'd given her got passed to her sister), it installed faster and easier with the seatbelt... EXCEPT... in my sister's corolla with some seriously slippery leather.
BUT... in fairness, I wasn't using a locking clip... AND my back was out... I was installing it because she didn't know how and always preferred I do it when I could manage... and I bit my tongue and did so... she was relieving me of caring for my only at-home child so I could rest my back (which really helped - next day I was fine)
ANYWAY... I couldn't get it tight with the locking retractors and the slippery leather, but I found the deeply recessed latch connectors (which were marked, so I know they were indeed latch connectors) made it WAY easier to install with latch than in my caravan or my mom's caravan, where they were exposed and very obvious and higher up.
One trick, though, when I would install it for my mother, as I used Latch as an excuse to pull off the slippery thick vehicle seat covers she put on her captain's chairs (with the boosters, I could use the excuse of having to turn the headrest around), was to pull it tight by pushing the armrests up, getting my knee in the seat AND pulling the latch belt toward my knee... as if I were going to belt myself in with it under the armrest... but it was tricky, as the latch belt was NOT long like the one on the Nautilus is.
Anyway... it can be done... but seatbelt is definitely easier in most cases.... and this is a seat that, being so lightweight, I definitely think you need a knee in, not just your hand... just for ease of install.
Now, if the Maestro (as it should, from all looks), installs even half as well as the Chase/Express (I had the Express and the Maestro seems to have even better beltpaths), it will be SUPER easy... I installed the Express for Jeffrey heavily pregnant without putting my knee in it in like... less than a minute... in our old buick that had squishy seats, long buckles, and that had separate retractors, with the lapbelt retractor being the one you had to pull out and lock to keep the seat snug...
we still had that car when we got the bolero, and while it installed well in that car, it definitely took twisting the stalk down 3 times AND putting my knee in it or it would still wiggle a bit (acceptable, but I like them rock solid, as I'm sure you know)