I've been adding portamento to my Korg Polysix and, on my first try, I found it not very exciting...nothing at all like the great portamento on the Mono/Poly. So, I did some analysis of the Portamento on the Mono/Poly and found that it purposely spreads the pitches of the individual voices to make the sound more interesting and exciting.
You may be interested in some of the details:
When I implemented this trick of the Mono/Poly in my Polysix, the portamento gained exactly the excitement that I was looking for. The designers of the Mono/Poly sure were smart!
Is this voice spreading typical of old analog synths, or was it unique to the Mono/Poly?