that’s 340mb … M has 1gb, which obviously needs to cover the OS, apps, drivers running and of course the rest of your patch etc. - but seems ok
(bare in mind, you only need to load the ‘loop’ if you are managing it, ie. you can stream if its just playback)
cpu, hard to say - entirely depends on functionality of your patch, and also how intensive your driver is going to be for the grid.
(if cpu is an issue, then you can make it multi-threaded , and so make use of all 4 cores)
generally, id always advise… give it a go… (or LMNC - dont be scared to try it)
prototype the bits you’re not sure about first, so you can refine/optimise these before putting too much work in the higher level stuff … at least thats way i work(*).
make sure you report back, always good to hear what everyones up too…
and esp. as the organelle-m is new, little has been reported on where the limits are, beyond technical specs.
(*) perhaps thats because i enjoy the tech challenges the most 
Ive been very pleased with the performance of the Organelle-M,
Im busy working on an Organelle-M setup, which uses MEC/Orac - that has an Eigenharp Alpha controlling synths in Orac and over CV.
The Alpha produces a ridiculous amount of data over USB, sampling is at 2000 sample (10bit) per second (!), I did need to optimise some of my threading and other code - but its working fine now.
so I think performance of both CPU and USB is excellent for this type of device, so I think if you have the will, its amazing what you can achieve on it.