Jon is the "current" drummer for Testament. J.Tempesta came in as well as A.Skolnick on "First Strinke..." because the band indeed treated that album as a side album to the progression of the studio albums and wanted to use members that had history on previous Testament albums. That's why I participated, I was on the last studio album, remember...?
Jon is also banging away with Eric in Dragonlord currently.
Darren is working with me and Chuck on our "side" project. It started out as Chuck's solo effort, but became our side band.
As well as the side project band, and Testament, and just having completed the new Vintersorg album, and whateverelse...I'm working on song ideas with Darren and Jon for the future when one day Sadus can make another album. So we consider Sadus still together, just idle.