I thought I read somewhere that an arbor isn’t needed if it has the texalium insert.

You put the insert inside the reel seat, let the epoxy dry, than install the reel seat like any other reel seat with arbors as necessary.

Some reel seat inserts, like the CFX reel seat insert, have a polyurethane core. So when glued in place you just ream the core to fit the blank. Other inserts don’t contain contain a foam core and thus need to be shimmed or arbored to fit the blank. I have not used the Alps reel seats with the texalium insert, so I have no idea if it has a foam core or not. In either case it’s not be that difficult to get the reel seat to fit the blank.
Norm

Spencer has you dialed in.

With reel seats, unless you're ordering the type that are fitted to the blank, you're going to need to use some type of arbor to fill in the gap between it, and the rod blank. If you look at the specs for the reel seat you mentioned, you'll see that the I.D. is the same (.531") for both the size 16 and size 17.

Yep, Spencer has you dialed in.

There have been some recently introduced reels seats that have a universal style inside on their reel seat. i.e. they will fit a large size variety of rod blank diameters with no reaming and no insert required. Basically, they have internal fins that are straight out for smaller blanks and fold back for larger blanks.

Be safe