What are the advantages of putting the MF investment into a disregarded LLC vs in my private name?  

Disregard ones owned by individuals, those aren’t syndicators.

I treat the LLCs as "disregarded entitys" for IRS purposes so no more book keeping needed.

Any P&I payments received can be disregarded because these payments go into the account as cash and are now a different asset in the account (cash) which is valued on its own merits, hopefully at face value :-).  

Prior to a 1031, does transfer of title to LLC trigger a tax liability or is it disregarded since it''s a single member LLC?

I disregard the interest, unless they actually view the property in person.  

The IRS looks at single owner LLCs as a "Disregarded entity" so the sub LLCs do not file a separate tax return.

Why hire me, then disregard my advice?

If not, please disregard what I'm about to say...You cannot use comparables that are over a decade old to determine current value.Start with properties sold within the last six months, in the same subdivision or within .5 miles of the subject property.

In your example I'd be stuck.If your using a contract that you can easily get out of if you don't find the right buyer then disregard.