I just checked out the Connecting Threads link - Thank you! They say it is 50/3 long staple Egyptian Cotton, which is exactly what I'm looking for.
I did some piecing with the Finca Presencia 60 wt yesterday, and the difference between weights is huge, so I definitely want to go with higher wt thread. The Finca is $4.99/300m on sale, so I'm all for trying some of the Connecting Threads :D