Hi,
Over the years I have owned (in this order) a Hammond M1 w/Leslie 145 (still have the 145), a Hammond B3 w/Leslie 122 (still have both) the Korg CX3 and BX3, the Hammond XB1, the Oberheim OB3squared keyboard and module versions, a Hammond BCV w/Leslie 147 (still have the 147), the Roland VK7, the Voce V5+/Spin II, the Roland VK8M, the Hammond XK2, a Hammond XB3 w/Leslie 122XB (still have both), and now the Hammond XK3.
Between the two models you are asking about, I would lean more toward the XK2. The VK7 has some advantages in that there are a limited number of non-organ sounds to choose from, but they are not all that exciting so... The internal Leslie effect of the VK7 may be a bit better than the XK2, however the Leslie effect in the XK2 is very programmable and I was able to tweak it to the point were I felt it was better than the VK7 or VK8M for that matter.
If there is ever a chance that you would want to use the organ keyboard as a MIDI controller for other external gear, the XK2 is far superior in this respect. The XK2 can transmit on up to four MIDI channels simultaneously and these can be zoned anywhere across the keyboard. The XK2 also has aftertouch and Pitch and Modulation wheels.
Obviously this is just one person's opinion (who has played Hammond organs for the past 30+years
) I am sure others will have differing opinions. If at all possible, I would suggest saving up more money and get the new Hammond XK1.
Good luck in your decision.
Dave
[This message has been edited by WDMcM (edited 09-15-2006).]