Good points.
And in my opinion minor mods to an already operational mill.
To the OP, the approach I took (and the one that this group suggested...thanks guys) is to take a hard look at what you expect to use your mill for.
What you are trying to determine is what size of working envelope that you need which translates into how big a table and Z height you need.
In my case I have small mills (Sherline/Unimat) for tiny work and extreme portability, an Enco 6x26 modified with a 7" riser and a Burke Millrite for medium sized work (both mills still portable by one man) and finally a Bridgeport for larger work (limited portability at best...ever carry a Bridgeport up three stories to an apartment? ;