I've put a Nord in my '98 stingray5 3eq a while ago...
Very nice sound, warmer than the original, probably as mentioned closer to the pre EB sound but I missed the authority of my bass. It wasn't the focused, uncompromising low mid presence I was used to. Not worse, just slightly different. But the bass didn't feel much like a Stingray any more. At least in my ears. Swapped it back.
If I had free cash I would have kept it and installed it in another MM or even OLP.
I guess it comes down to personal preference.
Talkbass MM Stingray club member #18
'98 StingRay5 '76 Fender Jazz Yamaha BBN5 custom Ampeg/PreSonus/QSC/a lot of Schroeders