I think that I like the Invader for the same reason a lot of people don't, but only in the context of the very specific tone I like. I tried numerous amps, guitars and pickups when we recorded, and I really, REALLY didn't expect that a basswood guitar with an Invader would be the one I'd end up using. Then again, I also didn't expect to record solos with a $20 no-name pickup from the GFS clearance page!
I can't think of any reason why I wouldn't like the Invader in alder, as I've always thought of it as being tonally in between ash and basswood, which (to my ears) sound great with the Invader. In basswood, it's got a bit more low-end chunk to it, and cuts through a bit more in ash; alder will hopefully fall somewhere in the middle. Regardless, it should be a major improvement from the stock JB, which I merely tolerate.
Meanwhile, I still can't comprehend why people like EMGs, yet they are the go-to pickups for the very style I play.