What are the specs for the Type S RAM? Will the memory modules for the TR work on the Type S?

The TR’s RAM will work but the S’s stock RAM is running at PC2700 while the TR runs PC2100 RAM.

No major performance difference; it is still compatible. But if you put your TR’s 512mb (for example) in with your S’s 512mb RAM stick the S’s PC2700 will run at PC2100 along with the TR’s. Regardless of what bank it is in.  IMO, the 1gig running at PC2100 is still a performance boost over using 512mb PC2700.