I noticed this old request for info and have just done this. Here is a copy and paste of my post from another forum.
Short answer is its a fantastic upgrade which is easily audible.
Jico SAS 1, stylus upgrade for P77 Cart
With the arrival of a new Jico SAS stylus for my vintage P77 cart that's fitted on my Rega Planer, just before Christmas. I thought it was a good time to also start taking my approach to vinyl playback a bit more seriously so a Hi-Fi News Analogue test LP was also ordered.
Key features of the SAS stylus 1 are it is of the boron cantilever and micro ridge tip type.
Initial observation, the Jico is so tiny the tip and cantilever look very delicate the tip is not visible with the naked eye and even with a magnifying glass it is hard to see.
After some fiddling with settings tracking down force was set at 1.20grm my cartridge set up was checked against the analogue test LP and performed well (which was a relief) in the entire test bar the most extreme tracking test
“Track 9: Bias setting: 300Hz tone, both channels +18dB
This track stands alone as perhaps the most difficult track for a cartridge to track cleanly. Although Its only 2dB higher than track 8, this track is perhaps the most famous of the four, as only the very best gear and alignments can pass it unscathed. For those with more modest gear, results from this track should be taken with a grain of salt.”
Well the TT has been going for most of the afternoon unfortunately any chance to do any objective listening during this period was scotched as my 8 year old daughter decided she wanted to have a disco but we had a great time playing and getting down to the Detroit Spinners, Boney M, Divine, B gee’s some rock and roll etc etc. The TT is only a couple of feet away and did not skip or miss a beat, tracking proved to be excellent. I love the simplicity and ease of use of the Rega for this.
Ok so later on I had a chance to make some better observation and comparisons to how the player performed against the original stylus.
Enough with the waffle. Improvements over the old stylus are immediately noticeable.
Clarity has improved across the board and with it increased resolution and detail retrieval especially in vocals which have more body and texture. Better treble detail which is smooth without tinnyness or harshness.
There is a greatly improved sense of soundstage and imaging it is much more precise and vocals have moved forward from being slightly recessed.
The bass has tightened up and is more controlled I initially thought there was less but that’s not the case it is just presented in a more coherent form.
It has proved without any doubt to be a very worthwhile upgrade and I am delighted with the results, not really expecting there to be such noticeable improvements from changing something so small as the stylus and not the whole cartridge is something to marvel at.