I made a switch to yoga and tai chi a few years ago and here are my results – I’ve lost a bit of my bulk yet I’ve stayed quite toned – leaner muscle, stronger in some ways – I feel like I’m in better shape than ever. A couple key points to consider… if you still want a toned, physically fit body you’ll probably have to select more physically demanding versions of yoga and tai chi – such as Ashtanga/Vinyasa Flow or Anusara for Yoga and Chen style for tai chi.
An additional point about pull-ups… neither yoga nor tai chi will effectively target this area so you might want to keep the pull-ups on the schedule. Oh, and in case you haven’t noticed yet… the clarity of mind… the centeredness/balance and presence found by practising yoga and tai chi tends to be much more attractive to others than the size of one’s muscles.