Fredrick's 99 was mine before I sold it to him.
The 99 has a stiff tip, and a softer mid and butt section than say, a Z-Axis. This makes for a rod that can sling some heavy stuff, but isn't so good at protecting light tippets.
If you want a great indicator nymphing rod, the 99 is your huckleberry. Not so good for midging. It also can really boom out long casts with dry flies.
More than any other rod I've ever sold, I regret selling the 99. It did so much, so well - but not midging. Wasn't a big deal for me, as I hate midging. Best way I can describe the action would be a 4wt butt and mid section, with a 5wt tip.