> How about no priority 1 incidents at 02:03 in the morning, resulting in sleepless nights until 07:30 - 08:30 every day during one's on call, wasted on stupid problems like ext3 filesystem corruption caused by lost writes (again: http://danluu.com/file-consistency/)? Is that a compelling enough reason?

I won't have calls about corrupted ext3, because I use XFS, so not much of
a point.

"No priority 1 incidents" is not a function of an operating system, so it
can't be a compelling reason to switch. You would still need to elaborate why
exactly Linux doesn't work, especially when it works well enough in most
admins' perception.

> A programming environment fully supporting standards.

Becasue Linux doesn't support a very important standard of... Could you help
me here? Nothing comes to my mind.

> Same software which runs on Linux.

Sweet. I should learn Solaris, so I can run the same software as I currently
can on Linux.

Do you hear how ridiculous this point is?

> Guaranteed application binary interface backward compatibility: compile on oldest SunOS 5. you can find, run on all the versions newer than that one.

Only ABI of kernel and (probably) OS-supplied libraries, which is not that
much when it comes to what most of the companies run.

> Change schedulers on the fly, as you need them. Realtime subsystem.

Of course, because Linux doesn't allow to change schedulers and has no
realtime subsystem.

> kdb and mdb: the best post mortem analysis tools in the industry (what are those system administrators going to do when the kernel crashes so bad that it locks up and doesn't dump a stack trace?)

This is a very distant benefit. One needs to be accustomed with kernel-level
code in the first place to make any use of these.

> Full security isolation and bare metal performance with zones.

You get bare metal performance with Linux containers as well, so not a strong
point. Only the "full security isolation" could be a sensible reason, but
then, it should be proven by close scrutiny. I haven't heard too much about
people analyzing Solaris zones, so I'm not likely to be convinced out of thin
air that this argument applies.

> Exhaustive documentation ("he who can read is clearly at an advantage"), much of it applicable to illumos / SmartOS:

> http://docs.oracle.com/cd/E19253-01/817-1985/

OK, let's go to booting chapter:
http://docs.oracle.com/cd/E19253-01/817-1985/hboverview-2546...

This is barely enough for a trained sysadmin to learn how booting works and
where to nudge when things go awry or how to do less standard tasks (e.g. I'm
not sure how much time would it take me if I needed to build a custom live CD
image; probably quite a lot, judging from boot(1M) man page).

Even if it's exhaustive, it suffers from not having much between
step-by-step-and-don't-think instructions and deep documentation that requires
prior understanding of the system.

> Should I go on?

You haven't provided many arguments that would be sensible reasons (let alone
being strong reasons) to invest in migrating to Solaris.

I think we should disengage from this discussion. If I was in (what I believe
is) your state of mind, I couldn't muster any good argument that would
convince my interlocutor.