I have the 4wt 99 and i really like it. I bought it with very little nymphing in mind. The reason i went with the 99 was for extra reach while fishing large dry flies in small pockets on fast water also for a little more hight when fishing from my pontoon.I had the south fork and the Henrys fork of the snake river ,and Utah"s Green river in mind when buying this rod. It does allot more than just nymph. I think it cast just fine and protects fine tippet as well. I don't have any issues with it being top heavy.
The other rods i looked at when trying to decide was winston IIx 10ft 4WT, Sage z-axis 1oft 4WT,and Scott s4 10ft 4wt. I thought the 99 was a more versatile rod and the others were a little more limited. But thats just one mans opinion.