I listened to the St. Louis Symphony concert on line this past Saturday Oct. 22nd. Apparently they are having guest timpanists this season. The principal timpanist of Milwaukee was announced as having playing Enigma Variations.

Maybe someone on the forum knows who will be playing later in the season.

You can listen most Saturdays at 8pm CT..9pm ET here:
http://www.stlpublicradio.org/listen.php

Here is the concert schedule:
(All Saturday Wells Fargo Subscription shows are LIVE.)
http://www.stlsymphony.org/concert/index.htm