I endured 54 years of AVRT. At 60 y/o, something is going to get me sooner or later. At least now, it won't be from SVT. I wouldn't be overly concerned about the dose you receive during the procedure. There is plenty of info on this subject out there. Google is your friend.
I just had an ablation for svt. My ep discussed the problems with ablating around the av node and I was quite concerned about the possibility of needing a pacemaker if the av node was compromised due to the ablation. He said that in the last 10 years, great advances have been made to better understand the AV node and reassured me that a pacemaker was very unlikely. I am SVT free and pacemaker free.
Just did some quick research on the other part of your question and found a site with some good information on the latest info. Very interesting! I thought the best info is in the conclusion where it states that overall there is less risk with radiation than being on meds for years or heart surgery. The site is: http://bjr.birjournals.org/cgi/content/full/75/891/253
Is this an assignment for grade?
;-)