Synchron Player users a Tree concept, as opposed to the ViPro matrix concept. Ultimately Synchron Player is more flexible because you can have more then 3 dimensions.
In ViPro you have matrix rows, and for each matrix row you have a 2D grid. (that's 3 dimensions). So theoretically in ViPro you have to issue 3 keyswitches to get to exactly the right articulation cell you want in your preset. one for the matrix, one for the X axis and one for the Y axis.
Often times in ViPro you can just send the X axis keyswitch and get to basic articulation changes without changing the Y axis and without changing the matrix row. So that is probably what you are remembering from ViPro, one keyswitch does that. To be explicit, you would technically need to send 3 keyswitches in ViPro also, one for the matrix, one for the X axis and one for the Y.
Now with Synchron, its a n-dimension concept...called a dimension tree. You can think of the first column (dimension) like the matrix row in ViPro, the second dimension is the X axis and the third column is the Y axis. You can change the keyswitch for the 2nd column (dimension) with a single keyswitch...and 3rd column slot position is remained in the position it is...kind of like ViPro sending an X axis switch and leaving the Y axis alone.
So that can all be done, but the question becomes whether the preset in Synchron is setup with the right dimension tree structure to enable you to commonly change articulations with a single keyswitch.
You can easily rearrange an existing preset into a different tree to your liking. the importnat thing to remember is that the mixer is configured for the whole preset. Each slot points to a channel in the preset mixer. So you can create a new slot in one of the other dimensions, right click on any slot you want to copy it, paste it into the new slot...and it should still sound exactly the same through the mixer, but now you use a different keyswitch to activate it. You could easily put you top 5 or 10 articulations into the first dimension (first column), and then they would fundamentally always be directly accesible with a single keyswitch.
This is a PITA if you have an older project you did with keyswitches embedded into the actual midi tracks...based on ViPro and now you want to play the project througth Synchron. The easier solution would be to figure out what keyswitches you were using before and rearrange the dimension tree a bit as I noted above to match ViPro's setup..then your project should play.
One advantage of using ExpressionMaps and ArticulationSets for keyswitching is that you could easily change the keyswtiches being sent from the project to match the new presets, rathe then having to customize the preset, but I digress.