I know this will sound odd,but the coders are so busy coding,that they pretty much seem to rely on testers and such for feedback,
Please keep in mind how quickly this technology is coming along,and I can only promise you,the coders work every day to improve the product.
It may be difficult to get an SL3 or 4 by itself(I am just now helping a lady I work with get started in the hobby,not sure what she plans to purchase herself,or I might could try to help.Depends on what she gets or does not get,and it could be a couple of weeks on that.)
Try the NEO-MAX software,the newest version addressed a lot of problems with the slim-loaders.
The only"cart"I cannot get to work with it is the NEO-Key.
Please just give the NEO software a try.
EDIT-On your side though.The SL's should probably be available seperately(they're kind of fragile)
Another thing-Boblen recommended to someone(as a LAST resort)to take the SL apart,and make sure the USB cable is properly seated inside.
Just don't hold me responsible.......