[nsp] 12.0(21)S3 or 12.0(22)S?

[Steven W. Raymond]

Have heard about generally good results from 12.0(21)Sx.  Cisco seems to
have recently introduced 12.0(22)S and one of the main selling points is
improved route processor backup failover durations.  I also note that
the RSP16 and VIP6-80s seem to first be supported with 12.0(22)S.
While all these new features may be neat, am more interested in
demonstrated stability than features.
Can anyone with experience with either offer their opinions of the code?
Thank you