If you want a complete package, probably the most powerful software out there, go with IS Boxer.
I too started out with Keyclone, and as far as broadcasting keys, it is very decent.

IS Boxer has Repeater Regions, or areas where the mouse auto broadcasts when it is within the area.
Combine that with an addon like Grid/Healbot/Vuhdo for click based healing, and you have a strong/easy method to heal.
You can do Repeater Region heals, with any software and a HKN script, see this: http://www.dual-boxing.com/showpost....4&postcount=11

IS Boxer/HKN can also do, "Send Next Click". You attach this to a hotkey which a ground click spell (Hurricane/Blizzard, etc), move the mouse on the slave screens/main screen in real time, and click instantly on all of them. Far superior to anything else.

Mapped Keys for IS Boxer are incredibly powerful. You can have the active window only, the non-active windows (slaves), all windows, members of a pre-defined group (Action Target Group) as the target of the action. There is incredible flexibility to do almost anything you want with these. If I was picking a single feature of IS Boxer as the strongest, I'd have to go with the mapped key system.

There is instant window switching, like Keyclones PiP swaps. Except they're instant. As fast as you can press the swap key or move the mouse to the slave windows and click.

You get automatic FTL assist. Just drag spells to any of the default buttons (1 through 0 and - and =) on each of your toons, no macros needed. On any toon, press your key and have them all cast whatever is on that key at the same target as the lead/active toon.

Lots of features that rock.