SOME of the photos on the webpage are fairly old. I used to supply Orange Drops as the standard caps and I believe Bob still does.
We use the 716P type which are film & foil, not the cheaper 715P type which are metalized film.
It's been about two years now, I switched to Solens, they are smaller and easier to fit on the board, and sound very good.
Two of the smaller .10uF's are in the signal path, and the other two are bypass for the phase splitter and not as critical.
The board will sound great with the standard parts supplied.
The PIO upgrade and the power supply upgrade caps are the biggest (actually rather small, it's already a great performer) improvements for the money. The PIOs need some burn-in time but will give you more "like you are there" sound, rather than slightly behind a veil curtain.
I haven't supplied the old blue Xicon caps for over a year, I know supply Nichicon caps which can be black or brown. The upgraded caps are also larger capacity Nichicon brand caps. They will give you more reserve for very loud or deep bass.