I don't think it's overgeneralizing at all. I mean we can go on and on about winding techniques and whatever else, but the magnet type is central to the sound. When I went through my EMG phase, I had the same experience. Ended up liking the SA / EMG85 the best for all the same reasons. The OP's comments remind me of exactly of my journey through pickups.
Brightest of the Alnicos doesn't make it harsh like a ceramic, or an Alnico 8 for that matter, which was my point. My opinions aren't original and I didn't say anything that hasn't been said before by people far more authoritative on the subject than myself.
The thing to remember is I'm pretty sure the 85 is not just an 81 with an alnico magnet. Is it's own thing. Else, they would've just called it 81A, the same they do to every other of their ceramic/alnico variations they do. I personally think the 57 is nicer if you want an A5 EMG, but that's JMO. It's not as stuffy in the low mids, and it's brighter. That's another example. The '57 is actually slightly brighter than the 81, yet it's Alnico.
And also, going back to my example, a '59B can be MUCH harsher than an Invader or an X2N or one of those extra dark overwound Ceramic pickups with lots of metal and an huge inductance value.
I do agree that if you compare the Custom and the Custom 5 which is as apples to apples as it gets, the Custom does come out harsher. But that doesn't mean the Custom 5 won't be harsher compared to something else specifically designed to take advantage of a ceramic magnet's high output and tight low-end, but not its high-end rasp.
I'm not entirely disagreeing with you either. As a general rule of thumb, yes, you're right, Alnico 5 isn't as "harsh" as Ceramic if you just swap the magnet in the same wind/construction/pot value, whatever. But I'm pretty sure the OP was stating he does like the 81, just that there's some stuff he'd change about it.
I'm like you. I'm digging the Fishman Modern Alnico in the bridge right now. I love the JB, the 498T, and hell, even the '59B (in the bridge, I hate the '59 in the neck). I tend to prefer A5's slight give in the lows compared to Ceramic, but that is not as spongy as A2. I prefer A5's biting high-end bite/twang rather than Ceramic's rasp (most of the time, not always, anyways), but you gotta consider people who like A2 often consider A5 as sounding harsh too. Yet I don't see you recommending the Custom Custom.
JMO.