The reason why people gem exp/crit and hit/crit (most of the time) is that you are effectively gemming mastery/crit when doing this.
Any extra expertise that is added to your gear via gemming means that you need to remove that amount of expertise from reforging, and as we already have crit on everything, it is eventually reforged into mastery via the 5-10 items that you reforge to get back to expertise cap.
Generally with gemming, I'll reforge all the expertise off my gear, then put exp/crit in every red socket until I fall somewhere between 2545-2600. Even with the "Wasted" overcap expertise up to 2600, it will still be slightly better than ignoring that socket in most cases.
When it comes to weird stat bonuses on a socket, such as +60 haste, unfortunately it will require knowledge of your characters stat values. Crit/mastery vary way too much depending on trinkets, tier bonuses and weapons to tell you an exact answer.
If you plug your stat values from simcraft into AMR (Don't use the import function on simcraft, it's kinda buggy sometimes), AMR's gear optimizer is actually pretty damn good about getting the best gemming solution for you, if you don't feel like wasting a bunch of gold or time.
This is how I do it:
1: Download simcraft:
https://code.google.com/p/simulation...downloads/list
2: Extract, run the simulationcraft.exe file
3: Import your character
4: Use these settings:
Make sure to set "Threads" to the amount of cores on your computer, unless you're doing other stuff. I have 4 cores, and I generally always set it to 2 threads because it will use every ounce of cpu processing power if it is set to 4, and I like to browse the internet and such while it's running. But If I'm running something overnight while I'm sleeping, I'll set it at 4.
Weapon dps isn't important enough to simulate, simply because higher ilevel weapons will almost ALWAYS win out, unless you're comparing agility vs str weapons.
5: Click Simulate!
Wait anywhere from 5-10 minutes, computer speed dependent.
It'll pop up something like this: (I cheated and did 10k iterations just as an example.)
** IMPORTANT** If you are overcap on expertise/hit (anything over 8%) the values for "Exp" and "Hit" will be wrong in your simulation. The simulation takes your stats, subtracts 1000 from them, and then finds out how much dps you lose from it. Under-cap expertise and hit are by far the most important stats, so if you're in doubt, just put them as the values listed here as they will not be too far off anyway.
Then you'll plug in the numbers into the edit function on AMR like this
Just leave AMR's default value for weapons on there, it doesn't change much from person to person.