[c-nsp] IOS upgrade suggestions for SUP32

[Lobo]

Hi everyone.  I'm in the process of configuring some IP SLA based 
commands and I notice that our core/P routers don't support it properly 
because of the current (old) code they're running: 12.2(18)SFX17

I've loaded up 12.2(33)SRE8 in our lab routers but also see that there's 
15.0S and 15.1S that's available for our SUP32s.

Are there any compelling reasons to go to 15.x or should we just stay 
with the 12.2(33)SRE8 code?  I recall hearing some bad stories about the 
15.x code a while back but not sure if that's still the case.

FYI, our core routers are not running much aside from OSPF (v3 for 
IPv6), LDP, and some static routes.  BGP was disabled for v4 but is 
enabled for v6 prefixes as we're not running 6PE.  It's as close to a 
proper P router doing nothing but swapping labels as we could do.

Thanks!

Jose