Not quite.
Although the "outer" dimensions of those bridges differ, all Legend, European and USA basses are listed at .75" spacing at the bridge for the 4's and .66" for the 5 and 6's (excluding the new wide 5 option which is back to .75"). I've owned, or have owned all 3 series and have never noticed different string "spacing" on comparible models. Also a couple NS2A's and their spacing was the same as My USA NS2, although the overall bridge was a little less massive.
They've even found a few of the last (Kramer) NS2A's were actual leftover USA bodies and necks that had inserts put in so they could be retro fitted with the NS2A sized bridge. There were no string spacing issues.
I'm just going by what PJ told me.
When I discussed the bridge options with him about a month ago, he warned me that
yes, the understood string spacing at the bridge is .75...
but he's seen issues where this was attempted on NS-2A models and several early neck-thru Korean models before the legend series and that there
IS a string spacing difference.
Perhaps a slight variation in string spacing alone wouldn't be an issue; but we've all discussed how the necks vary in width and/or thickness. So the combination of the two can lead to your strings being placed too close to the edge of the fret board and he seriously recommended against it.
And you also have to take string spacing at the nut into consideration. It comes down to geometry.
And I can guarantee you that although my NS-2JA-R has a Badass Bridge, so it doesn't really count (it's not a "Spector" bridge) the spacing on it is definately wider than that of my NS-2A or my Euro4LX.
So... Let me get my digital calipers out and measure the spaces...
The findings are:
STRING SPACING AT BRIDGE SADDLES - E to A Strings:
NS-2A (Korean Spector bridge)
15.5mm
NS-2JA (Badass Bridge)
17mm
Euro4LX (Spector Euro Bridge)
16.5mm
STRING SPACING AT 24th FRET - E to A Strings:
NS-2A (Korean Spector bridge)
14mm
NS-2JA (Badass Bridge)
15mm
Euro4LX (Spector Euro Bridge)
14.5mm
STRING SPACING AT NUT - E to A Strings:
NS-2A (Korean Spector bridge)
8.25mm
NS-2JA (Badass Bridge)
8.8mm
Euro4LX (Spector Euro Bridge)
9mm
LET'S MEASURE NECK WIDTHS AT THE 24th FRET:
Korean NS-2A: 59mm
NS-2JA-R: 65mm
Euro4LX: 59mm
LET'S MEASURE NECK WIDTHS AT THE NUT:
Korean NS-2A: 43mm
NS-2JA-R: 40mm
Euro4LX: 41.4mm
Isn't that interesting. There's a .5mm string width difference between the NS-2A and the Euro4LX, but they have the same neck width at the 24th fret and the Korean model is wider at the nut. But note that the Euro's bridge and nut are slightly wider regarding spacing that the Korean model. So there is a difference, but it's in favor of your argument.
And the NS-2JA-R has a monster wide neck at 65. It also has the most narrow neck at the nut. Meaning that there is very little room to mess with changes in string placement with this bass.
It also would not be advisable to put a Badass bridge on an NS-2A because you'd definately have string/neck alignment issues.
By these measurements; you are right. The Euro bridge from my 4LX, if properly routed and installed... should work fine with
MY NS-2A. But who's to say there are not width variations and inconsistancies between some models?
When my USA NS-4 arrives in another month, I'll measure it against my NS-2A and we'll see how that goes.
So the bottom line is... there are differences that although Spector tries to standardize things; there are going to be differences you might not have accounted for and therefore get a little surprize when you try to mix it up.
My point being, before anyone here attempts to modify their guitar, seeing that Spectors are not cheap and represent an investment to anyone who purchases one... check with the authorities at Spector before listening to anyone here.
PJ is the authority on that sort of stuff. So I was recommending he contact PJ, just to be safe.
That's all.