I have had an XD3 for 6 months now which is the module version of the XD9. I use it with either a lightweight 61 note keyboard or a fully weighted 88 note controller keyboard depending on the gig I play.
It has excellent solo voices and (IMHO)the accompaniaments are the strongest and best I have heard compared to Tyros, Pro9000, Technics 6500 (havent heard the 7000 live yet). I play music from the 40s through to now and many styles on the others makes don't cut it for me other than their swing or Latin.
It is full of features but you need to judge for yourself wether these are useful to you or not. You can download the user manual to discover what these are.
There were one or two bugs which were fixed by an updated OS and there are still a couple of minor ones but these are easily worked around.
The only downside for me is the lack of touch response. This is not a problem on the majority of voices as more realistic vibrato is included in most of the the samples where required but not on the guitars. You can get round this of course as all voices are editable and can be saved with delay vibrato (if required) as user voices.
There are other features that are really useful to me and one is the ability to change settings and save these on the factory styles. Another is the ability to lock part of the style arrangements so that these don't change with each variation. This allows me to use the factory styles on far more songs than I otherwise would. I can store around 30 extra styles (Patterns) in the user RAM which is enough for me but you can get extra memory if you need to store more.
I used to sell/play hammond tone wheel organs and there is a fantastic B3 sample available complete with the famous C3 (Chorus) vibrato setting along with other good hammond sounds. These are sampled with either fast or slow Leslie
The best part for me was the price - I paid £585 but had to buy it from another European country to get this price.
The SD1 the only other unit I would consider but this is too heavy to carry for most of my gigs and is far too expensive (for me). This has a slightly better accoustic piano but the XD is still very useable especially in the lower and mid registers. (I use a roland XV2020 with a 64MByte piano board for all my main piano sounds anyway).
Bottom line - try it out for yourself no matter what you buy.