wrote:

If TIS was only useful
for a year or two I'd consider it worthwhile. The Feds have indicated
that deployment of ADS-B in our area is a decade away.

I routinely fly across NY state and all the class C airports from western
to central and onto eastern NY offer TIS. Two years ago I installed the
Garmin GTX330 transponder that displays TIS traffic on an MX20 and GNS430.
It is definitely worthwhile in these areas.

--
Peter