This discussion about Ella's control over the body trait being better than MC's has been done many times in the past.
This idea was iffy at best back then, now it's even weaker thanks to new knowledge.
1) Whatever Ella can do, MC can replicate by stealing her memories, as long as he has enough power. He has proven this is the case by stealing the knowledge to create metal.
2) While Bramon says that Ella had fine control early in her career, now we know that he doesn't necessarily mean she could do it as level 1 or 2. She was already level 3 when she started creating her advanced forms with knowledge from her biology professor.
3) Level 3 MC is also capable of rebuilding nerves and blood vessels, as shown in the scene where he saves Laurie from Jared's bolt.
MC never had to put much effort to shapeshift in useful forms. He got the knowledge with his memory powers and mixed/matched the various forms at a macro level. Ella does not have the same capacity, so she had to engineer her forms at a micro level and it's obviously hard for her to do, indicated by her huge surprise to MC's poisons in deadend3.
MC is capable of creating far more complex materials, which shows that his potential in using the Body trait is very high, perhaps higher than Ella's. Once he reached level 3, he could replicate Valravn's armor material and more. We haven't seen Ella create any special material.
MC is capable of shifting between various forms very efficiently and quickly, easily add extensions to his base forms (like tentacles to his dog and eagle form), make highly customized forms on the fly (the huge spear, the blob that protects Amber and Liz from fall, his liquid form). Ella's shifting seems more planned and sluggish in comparison.
So no, her "finer control" is not enough to make her flat out "better" at using the body trait. It's a niche she has, but she also doesn't seem capable of functioning at a high level without it, while MC doesn't need it and his transformations are shown to be way more fluid than hers.