Talking about rhino nurbs geometry in revit families, and how ro keep them editable:

Importing Geometry from Rhino to Revit can be done with a lot of options, have a look at rhino.inside.revits dodumentation;

Direct Shapes, opening a 3dm and so on...

After a awfull lot of try and error i found my way of dealing with nurbs geometry inside revit families:

They simply have to be modelled with discrete values within the set tollerance, alongside keeping the general geometry as simple as possible;

What im talking about:

Currently we bought a 3D Scanner (FJD Trion P2) works good for now, i can import the pointclouds into rhino directly, via converting the pointclouds to *.e57; old format, but it works quite well, my current pointcloud is well over 6GB, no performance problems. I dont want to work with that awful revit recap plugin, i just dont get the point on how much work ive to put in to clean up the pointcloud and stuff, when rhino grants me a workflow of directly working within the pointcloud data;

So, old older buildings tend to be slightly off, no problem in rhino, huge problem in revit... again, why should i build a model, reduced to be "simple" when rhino has no problem of working with all this slightly off geometry...

I started modelling yesterday, made some nurbs geometry for walls that wont be edited and added anything else, like slabs and walls with visualarq, again, no problems for visualarq as well;

Next i transfered the data from rhino to revit via rhino.inside.revit; to organize certain nurbs elements like an "almost" historic staircase i started to create a revit family using grasshopper and i had one problem, that occured to me a lot: Revit isnt willing to import my geometry, because of small edges and stuff... ok, but there havent been any small edges, under 1mmm an do so on in my geometry, so i tried a different approach: modelling with discrete numbers from the beginning; and that seems to work for now, i can add subcategories, materials and so on;

My guess is: For the manually modelled staircase i started by drawing a line in z-direction between the two slabs, to get the height for the staircase, i then divided by 20 (acttually dividing the line with _divide), and that gave me a value of lets say 0.176. I drew a line between the points coming from the division and started to model with that curve; and that seems to be a fundamental difference between Revit and Rhino: Rhino says, ok you divided, the line is maybe 0.17654, but we show you a 0.176 because the tollerance is set to 0.001; revit says: figgu you, your nurbs edge is 0.17654 and thats NOT OK YOU IDIOT, we said the tollerance is 0.001.

So for now on, when ive to model for revit i type in the numbers by hand to make sure they are sticking to the tollerance in revit...

For me, working with rhino for 15 years, and having my workflow in rhino and so on its simply annoying to deal with revits behaviour of treating everything different... rhino got tools, and those tools work for everything: _split just splits, no matter what it is... Revit specified limitations and corrections for every single element and maybe they did that to gain more perfomance, like a way of optimizing things, but hey, its 2026 and pcs can handle more workload... till now ive never ever had any problems in rhino, concerning performance...

Really, what do we need revit for...