In fact, direct swaps of property are extremely rare.

This got me to thinking, with ductwork/wiring/etc already done is simply swapping out/upgrading the unit doable by a moderately handy person such as myself? 

Our old NG boiler is still viable & reasonable to run vs swapping it out for an on-demand system that I will eventually install, but I would them have a moisture problem all winter.

I am looking at rentals in that $60k-$100k range and would love to swap data. 

Missing possibly, but burnt out no.If you swap out burnt out bulbs for expensive ones like LED bulbs, keep the old burnt out ones and swap them back in when you move.Leaving empty light sockets invites thoughts of theft.Good Luck!

@Kevin Barry If the panel is a Federal Pacific one (Not sure if that is the same as an FPE) you definitely need to swap out the panel.

@Bryan M.Paint the cabinets white and swap out appliances to black, call it a day.

Also a new coat of paint or swapping out the door handles for modern ones can make a big difference.

The really bad ones can take an hour or even two (like swapping out a ceiling light where there are tons of wires and all of them are wrong).

@Dave Foster Can explain the swap/drop  vs drop/swap better than I can.