It all depends on what the current groupset is. The Dahon version comes with SRAM kit. Road STIs with MTB RDs normally have compatability issues. You need to search the forums. The problem I have is that the kit you are talking about is pretty low level, so I doubt that you will find much regarding suitability.
It's normally always worth upgrading to a full road STI set... the experience is significantly better (and lighter). My Espresso bike has Tiagra 2012. The black Jack was done with the latest Sora, which has a very good rep nowadays. I had the same conversation with the guy who did the Jack conversion. In the end, once your start to go road, it's worth the effort to go all the way.
On another point is weight. A road bike is light, the Espresso/Jacks weigh about 14-16Kg. You might have a bike with drops, but the weight is still chunky (and the wheels will be heavy and slow). If you put thought in the road kit, buy kit with weight listed, then you can get it down to 10.5Kg easy.
I hope that helps. Schocca.