Mosfets: The way to go for SS amplification?

You cannot really pin them down as which is better or what's the advantage of one over another. Each have their own operating parameters and do basically the same thing in the end: amplify a signal. How they are implemented for a given topology, the skill of the designer, and overall engineering from power cord to speaker terminals will determine their perfomance. Just one cog of many in a wheel.
For example, Nelson Pass used JFET's in the Threshold "e" series, IGBT's in the Forte's and MOSFET's in the latest "X" series. All different topologies and all, IMO, one hell of a good sounding product history.

"I've done a "search" here and elsewhere and not gotten a good answer as to why it may be superior to JFET"

You need to seek out some good books on the subject and explore the facts on your own (that would be my definition/approach of getting a "good answer"). I don't think the answer is within the scope of these forums, especially not in 5k posts.

www.audioxpress.com carries alot of books.

Thanks, everyone: as a layperson w/limited time to devote to the hobby, and VERY limited science IQ, I depend on my "friends" for help. Amazing what Nelson P has accomplished, BTW: can anyone beat this guy's electronics résumé? (Ez: if reading books would help, I'd have gotten a degree in a scientific field, and not gone through employment hell through these many decades; if we all had the time/innate ability...this forum would vanish!) Happy Holidays!

IMHO, it's not necessarily the parts, but the sum of the parts that matters.

A lot of folks think using mosfet drivers and bipolar output transistors give you the best of both worlds. McCormack and Theta are just two prime examples. People use to gripe about the mosfet haze but I guess times change. I think Jfet's are used more as an input amplifying device. I know there impedance stays constant over a wide range.