The plexi module goes after the cranked up side of the plexi tone, you can't really get a clean sound. The ds on the other hand is perfect for clean and dirty tones.
I was browsing modules and found this warning on Sweetwater today. What does this mean?
WARNING: This product contains chemicals known to the State of California to cause cancer, and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
The DS is unique, the original amp was designed with the jtm45 power section and the jcm 800 preamp in mind. The channels are voiced differently, unlike the BE or the HBE. Pretty much you can dial any classic rock sound and with the addition of the bright switches you can even get some VH tones...