Used to fly a 1980 J out of KLAM (elevation 7171), and have visited higher altitude airports in Colorado, If you have no mountain experience, take a mountain flying course with an experienced instructor; all NA planes feel different at altitude. High altitude must be planned for (temperture, winds, load), but presents no special problems for a well running Mooney. Primary issues are: know your POH, usually operate well under gross, especially in summer, depart early in AM to take advantage of lower tempertures, plan for downdrafts/updrafts (terrain, wind and heat related), and become familiar with changes to Vx and Vy at altitude. If I recall correctly, Telluride has steep slope to West and drop offs North, East and South. So, if you know the winds, you will know effects on your climb performance.