Starboard wrote:
As a astro-newb and soon-to-be owner of an 8" Dob (which for those not
familiar, can accommodate either 1.25 or 2" eyepieces & accessories), I
am clueless as to the advantages and disadvantages between the two, and
hence, also clueless into which size future investments should be made.


A very good question.

You might want to look around Cloudy Nights a bit:

Here is an article on how to set up a Dob (scope is similar to Orion XT-8).

Don't know if they have any 1.25 vs. 2" articles or reviews, but worth
looks.

FWIW, at this point in time, all my EPs, diagonals, etc. are 1.25" ..
though at least two of my scopes will support 2" accessories.

Phil