thanks for your answers.  it sounds like I can do what I want.
 
just to clarify things.
 
you mention: Supported sampler mappings at the time of writing are: EZdrummer®, Superior Drummer®, legacy dfh Superior and DFH® 1&2, Strike, Battery, Kontakt, BFD 1&2, Addictive Drums, Reason Drum Kits, SampleTank, Ocean Way Drums, SR DrumMasters, Steven Slate Drums, Drumcore, and of course any GM software or hardware sampler.
 
are you saying that I can use reason’s sampler to control EZPlayer Pro?  I’m not sure how that would work and what I could do with it.  can you expand a little as I’m new to Reason at the moment, and I’m still getting used to how it works.
 
Also, on the crossgrade option…. it’s cheaper for me to buy EZDrummer and the Crossgrade for SD2.0 than it is to buy just SD2.0 at my store.  so what I’m getting at is, if I buy EZDrummer and the crossgrade, will I just get my EZDrummer license totally removed and then a SD2 license added to my account?  or will I be able to use both if I want to because I did buy the EZDrummer full version as well as the SD2.0 crossgrade?  I know it sounds daft, but I save £20 that way, and I hope to then be able to use EZDrummer on its own sometimes too as that’s what I’m used to.