I am inclined to agree, though my experience is limited. I work on a
project that is trying to model all its software using Enterprise
Architect. EA has some nice features, but overall I find it clumsy and
frustrating.
Some problems are intrinsic to UML (for instance it has no concept of
linking use case information to other elements). And I don't know of any
way to model functions (only classes).
Others are EA's fault. For instance it is very slow and clumsy to add or
edit lists of items (such as class methods or database fields). Also,
shared development is a pain because there is no concurrent version
control (it uses CVS to keep track of revisions, but not in a concurrent
way; checking out a package locks out everybody else).
Version control of UML models is a tough issue, given the dependencies between
models and thinking of visualization of differences between two models. So
far my tool only uses one model in one single XMI file, but I have to change
this especially since I want to ease the re-use of components between
projects.
I tried using a competing product but the interporability was terrible.
Which brings up another point: it is likely the original poster would
need to do a lot of work for each CASE tool supported.
Unfortunetaly you are too right!

) Interoperability via XMI is a nightmare I
don't want to dream anymore. For example, in the recent years it would have
been much easier to use MagicDraw's OpenAPI with Jython to access models
instead of importing its XMI files. The one thing is that MOF, UML and XMI
are developing way too fast, so there are many tools but chance is little
that they are based on the same standard versions. Additionally I don't know
one tool which fully implements the corresponding standard specifications.
Not a big surprise since the specifications are really complex and extensive.
So, supporting one specific XMI format of one UML tool is not that
complicated (especially since not all features are needed). But I have still
a hard time thinking about an appropriate mapping between all these different
standard versions and the differences how they are implemented in the tools.
Especially since I want to keep these differences away from the normal tool
user. Maybe it will be possible, at least as some compromise. The future will
show.
Best regards,
Anastasios