After reading all the reviews for a new arranger (my X4 decided to stop playing for about 5 minutes on New Year's Eve), I finally settled on either the SD1 or the PA1XPRO. Being that there is a local dealer that sells both I figured the best thing was to do a side by side at the dealership. Due to the crowds at the store I used a pair of dealer supplied headphones to check out both systems. First, I auditioned the PA1XPRO for about 45 minutes (specifically since the navigation has changed considerably since the i3 (which I had been using to trigger the X4) I wanted to make sure that the test was completely impartial. Then onto the SD1. After hearing the two side by side attempting to use both similar systles and patches, I placed my deposit on the SD1, primarily based upon the ease of navigation and the more realistic sounds. My intent was to pick the keyboard up the next day. Do to the onset of what turned out to be a 48 hour bug of some sort, I was unable to pick up the keyboard as expected. Yesterday, I went back to the dealer to complete my transaction for the SD1 but something told me that, not only should I bring my singing partner (my wife) with me to evaluate the sounds, but also, I should try both systems again but this time though a speaker system rather than the earphones. Now, let it be known that I have not been a major fan of Ketron support, however, even with that in mind I had thought that, at least, the SD1 is a more mature keyboard than the PA1XPRO and based upon a variety of snythzone posts regarding the SD1, Ketron is working on improving their support. To make a very long story short, I am now the proud owner of a PA1XPRO based upon the sounds that I had, apparently, not been able to hear through the headphones (or maybe it was the oncoming cold). The sounds and styles are terrific the flexibility with the CD-R and MP3 options allow me to eliminate a variety of external gagetry. The good news is that the keyboard (50+ lbs) will remain, almost exclusively in the cafe (we used to move B3s and Leslies....not anymore) and just as the i3 was at the forfront of technology back in 1993, I believe that Korg support as well as seveal 3rd party vendors, this keyboard should be able to last for a good long time. One other thing for all of the keyboard players that join us at the cafe...this new 76 key keyboards has a real nice feel and should satisfy even the most discriminating player.