Your assumptions are correct. Preventor has nothing to offer the ID. Tennis in snowshoes, so to speak.
It has: No blend with C1/G1 continuity on all boundaries. No C2/G2 - not even in its vocabulary. No variable section sweep or swept blend. No section propagation options for sweeps. No exception handling options for failed offsets or shells. No conic rounds. No silhouette split or curves functions. Only the most remedial curve creation functions. No geometry integrity checking, analysis, repair. Rudimentary at best surface analysis functions.
In general:
It has a nice UI and is adequate to good for most mechanical design, even excellent in some respects, but is intimidated by the most demanding mechanical shapes. It has an incredibly annoying habit of going into deep thought for hours trying to create a poorly defined or sometimes just difficult feature with no way out except giving it the 3 fingered salute. Forget recovery. Save it beforehand or loose it.
Top down design capabilities are good, versatile, but difficult to manage, untraceable, limitations and pitfalls are poorly documented, and schizoid behavior like sub-assembly coordinate system origins inexplicably being launched into the next county seems to be considered acceptable.
Drawing mode is capable, but slow, surfaces can't be shown, is intolerant of translated solids and some curvy native solids. It has a predilection for corrupting drawing files or crashing when supporting model files are corrupt providing no indication of where the problems may be requiring hours to isolate, correct. It can sense when you are approaching deadline.
The industry is not all abuzz about Shape Manager. For all practical purposes you will find 3 - 4 year old ACIS with some minor tuning under the bonnet.
They try to convince you you are getting a good deal since you get Desktop with it, but you probably know how that is. Those that don't should contemplate the learning curve on two very dissimilar programs if both are needed to get the job done. There is precious little interoperability even some subtle hostility between the two programs and the more advanced NURBS functions in Desktop which are the best the combo has to offer are not parametric.
The pace of development has been underwhelming and they have recently resorted to an old tactic of purchasing 3rd party applications, ho-hum integrating them, charging extra for them, promising future development of functions they didn't create and might or might not understand. They will probably end up giving them to users as has been done after similar endeavors in the past.
Consider it for machine design. Think twice if you need to build around models translated from other platforms. Shun it for industrial or consumer product design.