Comparison of Cakewalk Studio Drums to EZ Drummer 2.0 and/or Superior Drummer 2.0

SONAR Professional and Platinum also include Addictive Drums2. Even SONAR Artist includes Session Drummer 3. All of these are more sophisticated Drum synth than SI-Drum.
 
SI-Drum is sfz-based like Session Drummer but the kits have fewer velocity layers. The SI-Drum kits play fewer instruments. The synth is limited to a single stereo output. Expanding the synth is possible but Cakewalk does not make it easy and there are no expansion packs made for SI-Drum. On the plus side, for those looking for a simple drum machine, this could be the one. The synth includes  compression and reverb which makes the presets more usable out of the box. SI-Drum can trigger up to 4 MIDI loops using MIDI notes 8 through 11. This lets one play loops creating more interesting patterns that just dropping loops into the MIDI track.
 
Session Drummer 3 is considerable more flexible. Each pad may be routed to a separate audio track. Sound files may be dropped on the pads to create a quick kit of 12 different sounds. Expansion packs are sold for the synth. The Session Drummer can trigger up to 8 MIDI loops using MIDI notes 27 through 34.
 
I do not have EZD2 but have the original EZD and Superior Drummer 2. Both have better sounding kits than the CW synths, EZD being more processed than Superior Drummer 2, although Session Drummer 2 includes presets using the internal effects and Toontrack sells additional preset packs for the various expansion packs. Both have the ability to send individual drums to separate audio tracks. Unlike Session Drummer 3, cymbals are not separate but are all played through the overhead track. Both have options to control bleed and separate room mikes. Superior Drummer 2 is even more flexible with much more control over each instrument and the ability to mix together pieces from any EZD or Superior Drummer kit. Superior Drummer 2 also includes an array of on-board effects and a very flexible mixer section. From what I have read EZD2 has a built in tool to create the drum sequence. Superior Drummer 2 includes an external tool, EZPlayer, to build up drum sequences.
 

No fancy testing here.  I have SI-Drums, Session Drummer 3, EZD2 and AD2.  I much prefer EZD2 and AD2 sounds over the Cake drums.  I prefer EZD2 to AD2 for the Song Creator feature.  Very easy to get a drum track going and tweaked.
 
clintmartin recently turned me onto an AD2 map (not a Cake drum map) that lets AD2 work seamlessly with MIDI laid out from EZD2.  This is a very cool duo for drums for my use.