On Nerdseq, first get some patience because it's a bear to get a handle on 80% of the things it can do.
The company is just one (occasionally cranky) engineer, and the documentation is... challenging.
Instead of getting more modules to feed, I'd recommend getting a Doepfer A-185-2 Precision CV Adder.
It makes combining and tuning CVs from Nerdseq a lot easier than doing it in the Seq's interface.
Much fun to be had there adding CVs together.
NS does a lot with midi too, and I liked the price and footprint of Xor's 2hp midi in/out.
You get lot of utility for the 2hp of space it takes. I put it on a longer ribbon cable for ease of placement and it works great.
The Video/Keyboard works well if you think you need that, but it causes a bit of a ribbon cable rat's nest.
I have a CV-16 Expander, but it's very much a seperate device as far as programming it.
The high effort/reward ratio kept me from using it much and it's back on the shelf.
In all, NerdSeq is well made, reliable and if you need to spit out series of notes that you set up ahead of time,
it's a great choice, especially if you enjoy a tracker paradigm interface.
I just got a Frap Tools Usta today (so beautifully made) and I'm expecting that it and the NS will get along wonderfully.
noodlehut.bandcamp.com