Correct. But it's not the "same", because the NSB stageboxes are no rack mixers. I would always recommend to integrate at least one of the rack mixers for more flexibility and as a backup strategy. Nevertheless you can use a rack mixer as single mixer. The 32R is the best choice. The 16R as a 16 channel mixer by construction does not really fit to network structures. All other mixers (not 64S) are 32 channel mixers.
I have owned exactly the same equipment as you and I know how difficult it is to change a running system (if it is still able to provide all functions you need). A lot of money is simply lost, the equipment you have purchased is nothing but "paperweight" now. I regret the few thousand Euros I have simply lost, but I do not regret having changed to the Series III ecosystem (SL 16, 32R, 16R, 3* 16M, SW5E). Besides the finally functioning AVB network with now 64x64 streams the highlights are SD Card recording, the Fat Channel plug-ins and the drastically extended range of effects. And you get a MIXER back to FOH, which makes a lot of things easier, especially the integration of Studio One into a live environment. USB at FOH is a blessing. DAW Mode is better on a CS18AI, simply because of more encoders and buttons and meters, but using DAW Mode with the Series III is also fun and works reliably.
But wait until WinterNAMM is over. You never know what comes (or not). And wait a little with the NSB stageboxes. There is still some "development" going on for this product.