If you send $2999 (the maximum), your effective rate will be $4.8219 after their fees. Send $2000, your rate is $4.7739. Send $1000 your rate is $4.6327...
Make sure to pull it from your US bank account and not credit card as you will be subject to higher fees as well as cash advance fees and interest.
I sent a deposit to my Galicia account and it worked perfectly.