Spectrum Analyzer Plug in for Tektronix 5103

Jan,

Which unit between a R&S UPL (low distortion gen.)and a Stanford Research ST1+ would you rather own?
Same for has lower distortion gen. and analog distortion measurement capabilities?
Same for digital?

Your thoughts about the Spectral Measurements M1 and M1E?

I see you as one of the most qualified to answer the above questions and give an unbiased opinion.

Thank you.
Wow - my last post here was 14 years ago. I can only tell you that in the end I got a used AP SYS2722 and have been using that for many years.
Used units go for about 8k I think.
But next best would be a used dScope III for half that and only a bit lower performance.

Jan