When I went from palms facing down to pinkys pointing towards the ceiling (pretty much), I had to half the weight. Getting back to where I used to be now but I'm sure I can feel it more in my rear delt too this way. I've never tried it with a cable, but sounds like it could work well.
That's probably because your rotator cuff isn't capable of lifting as much as your delts
Ok so i'm being a bit of an a$$hole with that comment but, the movement is genuinely a provocative test used by physio's to see just how pi$$ed off your RC is. I think you probably need to tear your supraspinatus to really "feel" how much the empty can targets it. This doesn't make it wrong it just makes it risky. Maybe the empty can really does eliminate the front delt. Since the front delt is an internal rotator, too, and we have just eliminated it, then maybe the RC needs to pitch in more than usual and this is just an unwanted side effect of more lateral delt activation. But then that assumes "feeling" = "activation" which may not be the case, and then we've opened a can of worms. It's kind of like lower abs with leg raises - is it your "lower abs" you feel or your hip flexors?
I've "felt" my lateral delts work doing lateral raises in the scapular plane (slightly infront) with the thumbs pointed towards the ceiling and I reckon I could make anyone feel them working with the right combination and approach of sets, reps and rest periods, and especially with pre exhausted front delts.
I think sometimes people are too quick to jump to other movements before messing around with programming of existing movements. I've had the chance to take this approach with a few people because i've worked with a lot of people with screwed up shoulders so things like the empty can are not an option at all. I have found most seem to "like" the cable version. My theory is simply that it is' a different line of pull than holding a DB.
However, the lateral delt machine is great for "feeling" it, too. I used this simply just to shut up a BB type I trained lol but now it's a quick solution I use for people who ask (i mostly get asked from people with beat up shoulders). I tell them to stop short of shoulder level, keep tension on the delt and do sets of 15-20.
I do have a theory that if you can't flex your lateral delt then it's pointless training it - "if you can't flex it, don't isolate it" - Someone smart said that but I can't remember who.