Wait for Demon9ne for an official response, but since I'm here...
Short version: Probably not, sorry.
Your items should not be compatible, your characters might be - if naked - but I wouldn't count on it, sorry.
Due to how D2 works; as opposed to, say, The Elder Scrolls 3 or 4,
which is to say using plugins instead of modding the base files,
until or - more likely - unless Demon9ne either releases the source files or custom-tailors the mod to only include the 'perks' you want, I except the answer to this is 'no' as well.
For what it's worth, Immersion does change the way you play Diablo, but the underlying game is still Diablo, imo.
Unlike some mods, the idea here is 'more and better' not 'completely different'.
Either way, have fun (should you choose to try it).