Dynaflight '10 is a slightly higher grade of Dyneema than Dynaflight '97. It's SK78 Dyneema vs. SK75 Dyneema. To get a comparison, original FF is SK65 Dyneema, 8190 is SK90 Dyneema.
450+ was (is?) the standard string material for Shrew bows for years. 450+ is 70% SK75 Dyneema and 30% Vectran.
My personal choice would be BCY-X. It's a second generation improvement over 450+ (452X was the first improvement over 450+, which was an improvement over 450 Premium).
BCY-X is 83% SK90 Dyneema with 17% Vectran. Very stable, even in high temps. Very durable, very quiet, very consistent. Best string material I've ever used, bar none.
I'm not a fan of fat strings, but I don't like "skinny" either. X is a very small diameter material. 20 strands is going to be similar to 10-12 strands of Dynaflight '97. I like 18-20 in the string, 24 in the loops (padded out with B-55).
So far I've heard nothing but great reviews on the X, and I have nothing but good to report from my own experiences.
Chad