Should your first full set be a concert D set?
Personally, the mellow sound of the flat sets is more appealling than the typical sound of concert D sets. But do you limit yourself considerably if the only set you have is a flat set?
The only limiting factor being that youād be more of a solo player unless someone you know has a flat set same pitch as yours.
ā¦or other instrumentalists were willing to drop their key signatures down to suit your tuning. 
Also, you will find tutorials are in D.
I think that Peter Laban pointed out in a different thread that all UP music is written out in Dā¦so as not to complicate learning tunes on other keyed (flat) sets.
And JOBM(in an Piobaire) once made the point he started on a Matt Kiernan C chanter, never had a spot of bother with it and that a flat would be worth considering for beginners. teaching a bunch of early teenagers struggling with NPU practice sets on loan, all concert D, I can only agree with Jimmyās suggestion.
(edited to clean up a typo)
Right. Itās been mentioned a few times.
John, are you aware that you have a piper in your area? I think Denny Hall lives on Vashon Island. He also makes pipes, including UP. He could give you lots of ideas. He also has a collection of old Uilleann pipes.
If you prefer the sound of a flat set then you have really answered your own question. However, why not purchase a flat set (full set or whatever) for your REAL enjoyment and a concert chanter for sessions. Just leave the drones switched off and play chanter only when in sessions. Anyway, from my experience in some of the big noisy sessions I canāt hear my drones anyway (or to tune them properly) so I usually end up just playing the chanter.
I remember Ronan Brown years ago playing a concert chanter plugged into his Harrington B set in sessions. He left the bass drone tuning slide off the set to keep it compact and drones switched off.
Wharfedalecarving.
I would say start on the Concert D set you have to look at other instruments to see that it is the normal thing to start on the most common then switch to the lower like look at Clarinet, people always start on the standard Soprano Clarinet then later switch to Bass or Alto or whatever, now I am not saying that the two are the same but you should hear play and have an appreciation for the standard pitch then if you decide to switch to/buy a flat set for fun go for it, but you donāt want to limit yourself to a transposing instrument if that is not the regular instrument you should know what the instrument is āintendedā to sound like before you go to something else.
Yes, I know Denny Hall. He lives in Gig Harbor now, on the same dirt road as Mike Saunders with whom Iāve played music for years.
Denny once showed me his old Egan set in boxwood, and itās been on my mind every since. Iāve heard through the grapevine that someone else in the area has that set now. Iāve also heard that Denny is teaching a young piper in Gig Harbor how to make pipes.
Thanks for all the great advice, everyone.