The only project I used was Glorp...but I will answer you the little I know.
 

Is a OODB that seems to work pretty good. Now it is very easy to install in Pharo using the Metacello ConfigurationOfMagma.
Notice that Magma work only in Pharo / Squeak as I am aware of.
Some people say the performance is good and other not very good.
 

GLASS seems to be an excellent choice for several projects. You can just download the VMWare and run it. I think it fits well for midium/big projects.
It is good that you can scale A LOT. OF course, if you scale a lot, you will probably have to pay. Look at the GLASS conditions.
Another important thing is that Gemstone is the Smalltalk in itself. It is not like magma. IT IS AN SMALLTALK, but that supports ACID ;)
So...you may have some little problems while migrating from Pharo to Gemstone as some messages may behave diffrently. Or maybe even don't have some classes in one smalltalk but yes in the other one.

Gemstone is headless. So, you cannot develop in Gemstone. You need a GemClient. So...and excellent choice is to develop with Pharo and deploy to Gemstone...
 

Glorp is developed in VW. The port to squeak/pharo is old. I only supports posgresql backend. To fix that, we developed GlorpDBX.
For more information, read: http://www.squeakdbx.org/GLORP integration
We have it working with PostgreSQL, MySQL and Oracle.
 
Cheers

Mariano