Just an Idea for your 2hp left.
Either keep them open for later expansion of a small nifty utility you need to accomplish something specific. Or something more utilitarian like a passive LPG, Meng Qi - DPLPG comes to mind (the frontplate is 2hp but the vactrols on the back are a tiny bit lager, which could make positioning a little tricky in such a packed rack.) Also it's passive! So you spare some Amps for the other modules ;)
-- zuggamasta
Ah thats a great idea actually! Heard good things about the DPLPG.
I was wondering, if with Ikarie you will get your filter-finger-fantasies covered. And then, with a heavy heart, sell Belgrad...(!)
Cause if you did you could seriously open up your rack some more! You could even get a small filter if you really wanted two, like WMD C4RBN which presumably is pretty awesome - and then you would still have a good amount of room left!
You could use it for another voice, an additional larger envelope generator like Quadrax or something and then take Cnoc out.
In general (and especially my own rack :S ...) I think envelope generators are underrepresented in a lot of racks. They are so nice for getting the best out of modules and adds potentially a lot of nice rythms to a sound/soundscape but also just simple voicings. E.g. with the help of something like Missed Opportunities to trigger them https://shop.cutelab.nyc/eurorack/missed-opportunities/