It's been just over 5 years since I've posted in this forum (wish I could say I've been practicing habitually in that time). I figured I should contribute someting
I had some...let's call them "old strings" on my beloved bass. A long Spiro Mittel E, a Spiro Mittel A (old), and Helicore Orch. D/G. The last two because I wanted a nice dark thump with the pizz. Of course, those two outlived their life and usefulness, so I went to the old string pile to see what else I had. I had, among others, some Corelli 380Ms. So I swapped the D and G and gave it a few days of practicing my jazz pizz.
I was a tad bit shocked. I was expecting a big difference in tone, feel, and...everything. While there are subtle differences, on my bass they are a fantastic match. Low register is...well, they're Spiro Mittles. They're awesome: low but not midnight-dark, not muddy at all, very clear. The Corellis have a subdued richness that I wasn't expecting. They sustain, they gliss well, and they have a very nice matching sound to the Spiros.
I'm not doing the description justice right now because I have trumpet students messing around in my classroom while I type this. I figured I'd throw this out there, since it'd be nice to have the nice (semi-pricey) low Spiros with a matching, more affordable top end. I found them an interesting alternative to Spiros on top, which are great...and a little brighter and stiffer.
Standard caveat: this was on my bass. If you get a chance, you might want to try the 380Ms on yours.