I've owned most of what they make in the Skyline range.
I've never laid hands on a US Lak, and don't want to, fearing they might, somehow, be worth the price difference.
First, still owned:
5502. Great combination of sounds, tho I'd prefer it if it were more aggressive. The Barts are smoooooth, a little too much so, even with stainless rounds.
Great, great neck, nice radius, smooth edges and fretwork. Beautiful wood, beautiful finish.
The preamp works well, the pickups may get replaced with Nord's/Duncans for more grind.
5501, still owned:
Loved the 5502, figgered that the 5501 would be "same bass, different and more aggressive flavor.''
It is that.
But as DKWilkins noted, the choice of harsh non-us pickups, and the also harsh MK1 preamp is, well, really harsh.
Shoot, there's several whole threads on XX01 mods.
Something will be done to mine; not sure what yet.
Otherwise, stellar bass. Kinda the opposite of the 5502 tho: I wanna calm this one down a tad!
The Hollowbody was the next aquired, still owned.
Flat out amazing quality. Fit and finish on a par with anything out there. Superb playability. The Barts in this are an excellent, excellent choice.
Wouldn't change a thing. Between single coil and dual coil, neck and bridge, there's worlds of excellent tone in this one.
Scheff: now sold.
Ergonomically, the best Jazz 4 I ever owned; the neck was just dreamy!
Sonically, an oddball.
Nice flavor, not so much of a workhorse tho.
C-ya...sniff.
JO5: still owned
Fralin equipped
Flat out, best passive Jazz bass I've ever owned.
Same excellent neck as 01, 02.
Beeeeeuatiful three tone sunburst.
Massively huge, clear, grinding J tone.
Records very well, blows holes thru a live mix.
This bass, and one particular 1981 G&L L1000 are my two favorite basses right now.
I hope this is helpful;
alan