Note on safety:
If you can't keep your finger off the trigger of a firearm when you are not prepared to fire... you shouldn't have a firearm. Don't use the grip safety on the XD as an excuse to develop poor gun handling habits. Train, train, train.
Glocks vs XD.
The Glocks are about 7 oz lighter than the XD.
The Glocks can use their big brother's magazines (your 27 or 33 can carry up to 17 rounds if you just buy the 22 or 31 mags with base plate extensions)
The Glocks are thinner and shorter than the XD.
27 vs 33
The 27 has cheaper ammo.
The 33 has more powerful ammo.