What is the point of modules that can’t be interchanged? I think we must be using the word differently.
The point behind modularity, and the Battlefield Upgrade Kits ( BUK), is you can swap out the mid section of each Vanguard, and give it properties of other Vanguards. The real question is whether you can swap just one side or the other.
There was a statement back two to three months ago, that all the Vanguards have a slot large enough to fit the Harby turret, so you just need the turret to upgrade to 2S3. Not confirmed but seemed authoritative at the time. There was no word whether you’ll be able to buy just the turret or need the entire Harby module. I for one think it will be easier to find a REO if she’s switching between 2S3 Ardor and 4S2 Rattlers.
The Vanguards generally have an EM of 29k, so anything but stealthy. However, the latest Sentinel is unique, that it has 1S1 and 1S2 reactors. Flying it with just a stealth S1 and shields off, it has an sig of 5k. Generally 6k can be considered stealth. So a Sentinel with the Hoplite BUK is a true stealth troop transport. That’s still new.