Hola and welcome to the forum.
I must preface this by letting you know I have not heard either of your speaker choices, and that speaker choice is highly subjective anyway. It's only your ears that ultimately matter to your brain. And unfortunately, you won't really know until you audition them in your room.
In addition to considering the basics such as power requirements and spl limits, the choices you have are quite different in regards to room placement. Given your small room, this is an important consideration. The RBHs will require less real estate than the dipole MLs. To perform their best, the ML will need enough room from the back wall to get the desired delay for the sound radiated to the rear. Not enough (i.e. too close) and it smears the image. Can your room accomodate the MLs placed well out from back walls?
In their favor, since you are doing 2.1, the added ambience of the MLs may work very well for you, making your room seem larger than it is, with more ambient sound than the RBH.
I would probably audition the RBH first. I use similar speakers in a smaller, well damped room in a near/mid field type listening arrangement, heavy toe-in, cross-fire type orientation, and the sweet spot spans the whole back half of the room; the ceter image is so solid, folks constantly ask where the center channel speaker is hidden. I use dipoles in a much larger, more lively, reflective room, where they have the room to really work their magic.
So consider the room, as the speaker/room aspect is 90% of the equation.