The Ruger Frontier is appealing for a few reasons...

.243 is right between .223 & .264.
Lightweight & short
Relatively inexpensive
Simple & unmodified or customized
Inexpensive 2.5x fixed scope

Downsides
Another purchase (I could shoot a lot of "match" ammo in an existing rifle for the cost of another whole setup).
No cheap factory ammo
Yet ANOTHER caliber to reload
Accuracy is unknown
"different" than either the "match" AR-15 or "match" bolt-gun[/b]