UPenn has world class electrophysiologists and they do many complex procedures there including the most difficult classes of VT ablations. Marchlinski and Callans have been there many years and they have added a few more top tier EPs to handle increasing case load. They are as good as you are going to get in terms of experience, skill and equipment for highly complex ablation procedures. Your doctor has done well for you.
I forgot to mention that they do have a fellowship program and you need to request that the principal operator for your ablation is one of the top guys and not one of the fellows learning. If they use their Stereotaxis system on you, then it is less of a concern with regards to risk of major complications even if it was a fellow handling the case. However, it would still be in your best interest to have the procedure done by the top flight EPs and with the fellows in supporting roles and not the other way around.