(found the link on a cached page. sorry, it was on another forum that's down right now; i forgot to update on this one.)
If it were me (and it's not), I would do the area you highlighted (except for the very middle with fine hairs) and the parts to the right with coarse hairs too with laser. It's up to you if you want to do a 3-5 hour electrolysis treatment there instead. Having had electrolysis with 4 various electrologists, I'm not positive that it would only take 3 hours with an average electrologist for your first clearance of that entire area, but 5-6 hours is probably right on average with thermolysis. Dee is fast I'm positive, but it would depend on who you can find in your area.
You would also need to factor in going in every couple of weeks after that for another hour or two to zap the new hairs. It's a commitment with either method. With electrolysis you do need to go more often. I can only tell you what I would personally do as others are sharing with you too. In the end, it's up to you what risks are worth it and how much time you are willing to dedicate to this.
you may also want to contact TomGraham, a longtime poster here who was getting electrolysis for 2 years on his back and decided to try laser because it was taking a long time. he had one treatment with good results so far. You may want to contact him for an update as he last updated us in May:http://www.hairtell.com/forum/ubbthreads.php/ubb/showflat/Number/42345/page/0/fpart/3