I spent some considerable time yesterday evening working on this issue. Whilst there is much that will need the passenger-and-mail classes branch of both pakset and code to get right, there are also substantial changes to simuconf.tab settings based on the work that I undertook last night that will be the default in the new version of the pakset when the passenger-and-mail classes branch is integrated with the master branch and released which you can apply now to improve the passenger generation. Indeed, you will need to do this manually in any event, even after upgrading to the next version, if you want these changes to affect your existing saved games, as simuconf.tab settings are always saved with the game.
To change simuconf.tab settings in an existing game, load the game and press the "i" key. You will be presented with the advanced settings dialogue. Be careful changing these settings, as they are intended for advanced users and can cause problems in your game if you make an erroneous change. However, there are three specific settings that you should change to obtain the benefit of the improved passenger generation calibration that will be in the next version.
When the advanced settings dialogue opens, select the "Extended" tab, and then select the "Passengers" sub-tab. Change the very top setting, "passenger_trips_per_month_hundredths" from 60 to 156. Next, a little further down in the same list, change commuting_trip_chance_percent from 67 to 20. Finally, in the first table, change the second row under the column "journey time tolerance min. min" (the row being marked "visiting") from 3 to 8.
These settings should give something approximating the calibration that will be achieved when the new version is released.