Besides the fact that there are more colors of Spicas.

Have any of you compared these two products?

yes,,,,,I like them both.

MS are a bit jucier, so if you like that go for it,,,,

the spica ones are very cool, but not as juicy and have a smaller tip for fine detail.

Both. Okay, that works for me

I like the Sakura Stardust pens for glitter pens. I haven't used the MS ones though. I have a set of Spicas and they're OK...but I like the Sakuras better. They have more sparkle.

sounds like I need sakuras

That's very interesting, Amy, thanks!

yep! I also use the Sakuras for coloring in stamps. You don't want to use them on huge areas or it takes a long time, but they give a beautiful sparkle to stamped images!
I used them on the carousel horse on this card. They're opaque, unlike the Spicas which are pretty see-through.
Whimsical Carousel By Here Kitty
**The coarse sparkles are loose glitter (mane/tale), but everything is colored with the Sakura Stardust pens.

And the lemming for Spicas is officially killed, thank you. But I do need more Sakuras

What Amy said!

I wouldn't mind getting some spicas for the times that I want a more subtle bling, but for full-on, excellent coverage, I prefer my sakuras.

I have only the clear Spica. I love it!!! I use it over my regular copic pens to give my stamped images a touch of glimmery sheen. It's also great over pp.

Amy, your card is so pretty!

Oooh, now I really want some Sakura Stardust pens. And if I remember correctly, I think I saw a Scrapbook Memories TV episode one time where they actually used the stardust pens to watercolor with, too. At least, I think it was the stardust pens. I'll have to go see if I can find the episode online to see if that was the pen they used. I like pens and tools you can use for multiple purposes and finishes like that (straight out of the box, or with other mediums).