You mean http://www.hannigantrikes.com/
(no c in trikes)
The Hannigan triple is also $1000, kind of on the high side.
Talk to Brian Venney about his triples, they're as nice as any others & priced a little better.
No surprise you get more info about Roadstars here than Royal Stars - being the Roadstar Clinic & all.
To answer the original question, the Roadstars & Royal Stars triple trees can be freely interchanged with each other.
What fits one fits the other - at least as far as the neck, bearings & fork tubes.
What will NOT fit is the headlight, even if it's a Royal Star Tour Deluxe or other version with a stand alone headlight.
If you're going custom or just swapping Road~Royal triples, you'll still need to modify the headlight or it's mount.