Lynn, I'm only a half inch or so taller than you. My 5 Spot was a small but the new Solo is a medium.
Yes, yes, yes. Try everything and see what fits and works for you. Funny thing is I'm shorter than Quinn by 2" but we can usually ride the same size bike. The Mach 5 is a stable bicycle that will do anything. It's solid and is not "tricky" to ride on the downhills - very predictable. I wanted to combine my 29er XC bike and the Mach 5 and it seemed 27.5 would fit the niche. When I tried the new Turner, I immediately noticed the lower bottom bracket height and the comfortable body position when on the saddle. The Flux 27.5 climbs efficiently (rode B* on Sunday in the heat and made it to the golfball) and on the descents it makes me giggle - it's that fun.
Been a flux rider for years. Hated to get rid of my 26" but forced to due to damb manufactures. Cant get certain parts anymore. Went kicking and screaming to find new ride. Settled on new Flux. Love it. With DB shock its awesome.