Yep I can confirm it. I would say it like this. If you want a extremely clean surface model it is faster and easier to do in ICEM.
And as you pointed out the reason is its fundamental different approach of approximation instead of interpolation. Whatever you do in ICEM (if you run in it in Design mode) you anneal a given surface patch to whatever you want to do. You want to offset, so you define the surface properties first and then it tries to get as close as possible to the computed point net. This gets rid of the post process like you have to do in Rhino after any operation. And ICEM approximation algorithms are one of the best. This becomes especially valuable for complex blendings. Difficult corner blends (if you know the surface layout of common corners like T, Y,X and other junction blends can be created extremely fast and flexible in a complete manual process. Newer ICEM versions even create some corner blends in highest quality automatically.
It feels more like construction than design and of course this “as-close-as-possible” mindset, requires you to check anything twice. Does the continuity match? The curvature may match, but there is a positional mismatch. On the other hand ICEM is the only tool which gives you enough analytic power to actually match a surface only by moving control points. On a difficult blend, optimizing the matching manually is extremely powerful.
My experience from automotive design is that if you want highest quality you ask a ICEM specialist and if you want it quicker you choose someone using Alias.
Now Alias becomes better in class A from day to day. Some even switched from ICEM to Alias already. And yes the GUI and UX in general is not the best. I think why ICEM is so common in automotive industry, is because it had been developed in strong cooperation with engineers and designers while doing everyday work. And as a specialists tool it’s not good in other things, but quite straightforward for anything you do for creating a car skin. Latest development however focused more on project management, since OEM’s usually see modelling as contract work. So they need mechanisms to evaluate others work, instead of improving workflows. It scares my how much is outsourced nowadays…