Lots of thoughts and perspective. TLDR: If you want drums: Go Grids. It’s a fantastic module.
The Marbles’ drum algorithm is clever (of course) but consists of a few partial patterns, where one side off the knob filters the “snare” hits out. Essentially, every 4 tics, the current pattern in the Deja Vu buffer determines which of the partial patterns should be played. It works really well, but like the rest of Marbles, isn’t really designed for intentional work. You merely get to tell it how much to change and to shape those changes. The bonus is the patterns are pretty reliable, Grids has a really diverse set of root patterns based on computational musical analysis. The result of that means not everything is “useful” for everything. The beats from Marbles are somewhat bland but work for many kinds of music at many tempos. (And obviously only give you kick-and-snare-like patterns.) Additionally, the Jitter algorthim sounds nicer than the swing that grids provides. Oh and this is key: You cannot reset the drums from Marbles without modifying the firmware (you can hijack one of the clock inputs for this). Alternatively, you can force sync by temporarily patching a Marbles kick into the reset line of any other modules that needs it. Awkward, but worked well for me in the past.
Grids on the other hand is an exacting tool. It has 16 master patterns which smoothly morph based on the X and Y knob positions. The patterns data lets you choose how much of each thing you want, and for the most part that is intuitive. That said, it also has a certain degree of obfuscation because the “map” is largely unknown, and learning it is extremely difficult. To some extent there is still an element of “surprise” in that you might twiddle the knobs and have no idea what will come bad. They’re arranged based on similarities within their structure, but there isn’t any kind of guide to suggest what you might find in any given “region”. The plus side is that it is proceedural, not genrative, so the same setting will always give the same results. (It’s worth noting that the pattern data has quite a fine level of resolution (256), so with some of the patterns, even very small knob movements can lead to subtle changes. All of that said, the panel layout is solid. I’m a propronent of inverted front row usage. It’s a very easy module to play and appreciate in many arrangements. For more Marbles-like behavior, the Chaos knob (availabile in lieu of swing) lets you introduce random variation. It also makes a decent master clock.
That said I wrote a kind of replacement for Grids for crow precisely because of those “weird zones” for the music I was interested in making with it. I will keep Grids around tho. It was in my first modular order, and it remains a pleasure to use and explore. Quite probably my favorite module?