Just a couple of brief thoughts:
I didn't pick up anything else last night til right before I went to bed.
In it's own context, the Alleva neck feels great. Compared to my RV5, the neck feels a tad wider. This does nothing to diminish it's comfort or playability, just noting.
It sounds "very organic" compared to the other active JJ's I've become accustomed to over the last year or so (see sig line).
Sonically, it kinda "lays low" til you really dig in on it, and then it says "yeah, I've got snap, you just gotta ask for it." For this reason, I may move away from the DA nickels that are on it and go to something a little brighter...but, I'll use it in a band context first.
This is probably in large measure because I've become really addicted to the whole Sadowsky thing lately. The LG is very audibly different from that...neither good nor bad by nature, just a different thing.
On a strap, it seems "to lay a little more to the left" for some reason. I find myself kludging around on it instead of being able to accurately shift from one position to another without looking; especially in the lower positions. I play with my eyes closed a lot, so that matters to me. Dunno why that would be, the top strap button seems to be at 12th position "like most basses," so maybe the tail end of the body is a bit longer than my other JJ's...or, maybe I was just a dork last night

Probably just "an acclimation thing."
The preamp is overall very subtle, and you can use a lot of it without it "sounding active" if you care to. You don't need to though, which is nice.