The AT Pro is lighter than the GTI 2500, you can swing it for hours.
I used to own a GTI 2500 15 years ago. Found my oldest coin a 1905-O Barber Dime with it. Didn't think a thing of the weight, I had strength then. I'm 66 now, less strength, I suppose.
I owned an ACE 250 for a year. Got spoiled over the weight, ease of swing, simplicity of use. Found hundreds of coins.
Now have an AT Pro with the 5X8 DD Coil. Seems as light as the ACE 250, easy to swing. You trade an "image" from the GTI 2500 for detailed sound on the AT Pro.
The GTI 2500 offers easy to read size information. The AT Pro has great sound and ID information, but no size info. You get an idea of size by pinpointing with the AT Pro.
AT Pro is waterproof. The AT Pro takes me a little longer to set up because of the waterproof "one way" connectors for the coil and headphone.
You got to get them "just right" to slip in with the o-ring and offset connector. The cam lock shaft on the AT Pro takes a little longer to attach, but is very stable.
One thing I'd for sure do regardless of which detector you choose. Buy a Garrett Pro Pointer!!! This single item will compliment any detector and make it so easy to recover targets.
I'd get both the AT Pro and the GTI 2500 and try each of them out. You can always sell one or just keep them both! They are both easy to sell and both are in demand.
I've traded with Texas Premium for years. Stick with Garrett and enjoy!