Working for SUP vs. Working for MSC

Hi Everybody,

For 2 years, I've planned to leave the navy and go to work for MSC.  I
got my AB ticket/STCW/RFPNW/etc, etc...  Now I have about 6 weeks
left.

A few days ago, I happened to be in a commercial CelNav class and the
instructor mentioned that I was about to "shift berths" over to MSC. 
Everyone in the room looked at me like I was nuts.  They proceeded to
explain to me how I was nuts, that I should work for <insert favorite
union here> instead of MSC.

I've looked at a couple of Union websites, but I don't feel like I
have the whole picture.  The following are some arguin' points that
I'd love to get some feedback on.

1) "MSC's claims about leave time are exaggerated.  After a couple of
years, you get a much better leave package working for a Union."

2) "Your yearly take home will be higher working for a Union."  I hate
to sound like a squid, but is there a pay chart somewhere that I can
look at?

3) "Your first year will be on a LMSR, they're always sailing short." 
Why do the hiring halls have such a hard time filling billets on
LMSR's?  I understand that they're underway a lot, but are there other
downsides?

4) How does a union pension compare to federal retirement?  Is this
apples & oranges?

5) Getting OINCNW training for 3rd Mate: seems like MSC does this
better than the unions.

6) Shore leave & ports of call: is there any difference?

7) Homeports: in theory if I was working for MSC, I could work west
coast for a while and then go to europe for a while.  How does
switching coasts work?

Thanks a million for your input!
TJ "The Short-Time QM2" Willis