I bought the SL88 Grand two years back, when I needed a proper 88 keyboard, to emulate a piano-like playing experience. I use it in its most simple way: Take a MIDI cable, connect to a Nord Electro, and play piano/electric piano on the SL88. I had Studiologics before, so I knew they are not very "roadworthy" (external power block, cheaper materials).
The keybed, with its wood keys and triple sensor technology, is a joy to play - so far, so good.
But after a year of - light - use I noticed the first "stripes" on the TFT color screen (where the light cells don't work properly anymore). By now a second row of cells has gone, and it is basically waiting for the TFT panel to break down completely.
I can't comment on the quality of the software, but I can't recommend buying this keyboard any more, given the quality issue I have. Imagine you want to use this as a proper master keyboard and are depending on the screen to work ...