Strange, that's not fixing things... I can get the LCD117 working on the regular serial port though, if I gang up what I send it so it happens at once; makes things much better.
Using softwareSerial with ShiftPWM and either serial display isn't working for me at all though, I wonder if anybody else has tried?
This is the SparkFun backpack I'm using: SparkFun Serial Enabled LCD Backpack - LCD-00258 - SparkFun Electronics though the one I have is ~2 years old and may not behave like the newer ones.
Anyway, I'm up and running with the LCD117, many thanks again for this awesome library!