Like I said in a sticky post, I don’t do CPC for now, so no new version planned.
However, I can assure you that AT2 is the most fully-featured soundtracker for AY :).What you want to do exists already.
– For the vibrato, use the P command and create a Pitch Table, with value 0,1,2,1,0,-1,-2,-1 for example. There are many ways to make a vibrato, so it was much interesting to consider it as a pitch than create a Vibrato command that would surely be limited. Open the “A Harmless Grenade” to see some examples.
– As for the volume glide, the I/O commands are extremely precise, timing wise. However, please note that the AY only has 15 volumes, and is logarithmic. So the volume difference between F and E is much bigger than E and D, and so on. So doing a really slow fade in/out will reveal these steps. One trick is to use softer sound (starting at D for example). Another, if you are using two fade in/outs in two channels, is to shift them so that the steps aren’t hear both at the same time.
On a general side, I suggest you open the “Hocus Pocus” demo song, there are a lot of tricks inside.
If you miss any feature, let me know. But I can assure you that AT2 can do 100% of these old songs without any problem.