Hi, I have not been able to hear the floorstander in my own system. Nevertheless, my recollection under different circumstances is that the overall characteristics of both models are very much the same, which is probably not a surprise given they have the same coaxial drivers configuration. The "gospel" would suggest that the floor ported design and additional air in the floorstander deliver deeper bass, the larger cabinet on the other hand may store more energy leading to a less fast reponse. I can can put your mind at rest as to both. With the Diva Control unit you can achieve a similar frequency response with the monitor (btw if necessary you can also use the Diva Control with the floorstander). The floorstander IS a fast speaker as well, IF it is less so than the monitor, then I have not been able to distinguish it when I heard it.
Bottom line: if your room is fairly large, go for the floorstanders, they will deliver deeper F3 without need for the Control unit, thus retaining the entire glorious 97dB. Otherwise, I don't think you will find the monitor lacking but you will probably want to use the Diva Control and that will lower the available sensitivity of the speakers. In both cases, you will have a fast (but not nervous), neutral (yes, the Control unit will explicitly not change that) and extremely musical (buzzword, but the best to describe the essence of the sound) performance.