So, there are pros and cons of both of those types of procs. We’re trying a new system for these enchants. This new system, nicknamed Real PPM, aims to give the random nature of procs, the scaling with haste, and the ability for us to balance them assuming a standard proc frequency. Here’s the short version of how you can expect them to function:
•Windsong is 2 Real PPM, and Elemental Force is 10 Real PPM.
•Come patch 5.1, Dancing Steel and Jade Spirit will be 2 Real PPM, River's Song will be 4 Real PPM, and Colossus will be 6 Real PPM
•Regardless of how you’re attacking or healing, slow or fast, with DoTs or direct heals, whatever, you can expect to get the same proc frequency, on average.
•Dual wielding and having both weapons enchanted with the same enchant will double the frequency of procs that you get.
•This Real PPM is increased by your haste %. (The highest of your melee, ranged, or spell haste is chosen).
•Simple as that. Whether you’re an Affliction Warlock dealing very frequent DoT ticks and Malefic Grasp ticks, or a Holy Paladin casting purely Holy Lights, or a Combat Rogue quickly attacking and using specials, or an Enhancement Shaman attacking with slow melee attacks and spells, or a Shadow Priest channeling Mind Sear on fifty Onyxian Whelps, you’ll get 2*Haste Windsong procs or 10*Haste Elemental Force procs per enchant per minute.
•We’re excited to see how this proc system works out. If it works well, we may start using it for more types of procs. Feedback about how it feels is most welcome.
Here are even more nitty gritty details, if you’re interested:
•It can proc from any damage/healing event. It keeps track of the last time it had a chance to proc for that enchant.
•It calculates the difference in time since the last chance to proc. It uses that time to determine the chance for that event to trigger a proc.
•For example, if you have 22% Haste, it was 1.4sec since the last chance to proc, and you’ve got Windsong, then the chance to proc is 2(ppm) * 1.22(haste) * 1.4(time since last chance) / 60 (sec per min) = 5.693%.
•The ‘time since the last chance to proc’ is capped at 10sec, so that your first attack of a fight isn’t a guaranteed proc.