Infraction: 1. All posters are to make an effort to communicate clearly.
Message to User:
This is getting old. Capitalize and punctuate properly or I'll just ban you permanently.
I do know for sure that overhealing is very strongly affected in going from a 5 man to a 25 man. My own overhealing at least doubles and sometimes triples. Because I'm a bit of a control freak, I tend to like the 5 man healing environment more in many ways because I have a lot more control over everyone's health. They may pop a health potion or something like that and mess me up, but otherwise I have a great deal of control over prioritizing heals in a way that keeps everyone up in an efficient way.
Part of that process is choosing the right-sized heal for the job. Frequently that allows me to know a flash heal isn't going to overheal at all since I know it won't take the target to full health. However, I'm generally not expecting a crit heal, and I don't know how much I hedge my heal size to account for possible crits. So I'm sure my crit heals would overheal more frequently than non-crits, and the only question is "how much?"
In a 25 mans, health bars are often moving very frequently and in both directions. It becomes very difficult to predict what the right-sized heal will be when the heal completes. It's often zero. Crit certainly introduces even more variability, but everything is so random that crits are not your major problem. I worrying less about crits and instead focus on guessing what other healers are likely to do. For instance, if someone (usually a dps) unexpectedly takes a "conspicuous" unexpected hit, I tend to ignore that because I know every healer in the raid just saw that and some of will surely be healing that target. Such a target will either die before anyone can do that or will get massively overhealed, so I often ignore that and try to heal someone else.
Anyway, I don't want to digress too much into how healing tactics differ in 5 vs 25 mans, but the point is that crit is a relatively small source of variability in 25 mans compared to interhealer competition. In a 5 man, there is no interhealer competition, so it seems reasonable to predict that crit would have a bigger effect on overhealing in 5 mans than in 25 mans.
In 25 mans i rarely if ever use my GH. It's all FH BH and CoH. Even if im stuck to a MT healing spot on a boss fight ill still use FH and BH and bairly a GH reason being because 9 times out of 10 you will be grouped with a palidian for the other MT healer. GH has no chance of standing up to their fast big heals. I heal off of crits, i just spam FH and when i know i need a crit ill pop a BH. I dont know the numbers but crits for BH seem to be much higher than any of my other spells ill take a 10k crit BH over a GH any day.