I think a lot of plants have the most energy right when they start to spring back to life this time of year. That you can do all sorts of torture to them now and they will recover just fine because they are so pumped up and actively growing. But there is this touchy period when digging and dividing or potting up upsets the balance. There is basically no way to determine when that magic moment is - so I say, if the sprouts look healthy go ahead and dig and pot up. If the plant looks weak, leave it alone unless you would rather go ahead and replace it. In my fruit area I have plenty of doubled up plants, because I thought one was dying so I cut it back and planted a new one only to have the original plant return later and now I have two of them growing side by side (when they get bigger, one of them will have to go).

Here's some info from King Co, WA http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/creeping-buttercup.aspx Here is a link that might be useful: info

If the heavy soil is killing the flowers buy lighter soil and dump it on top, without mixing it with the existing soil, plant in that. Or choose adapted flowers. You will have to do the same with shrubs, if the kinds you want don't like clay soils they won't be any happier with the existing soil than the flowers were. Is there a hedge, wall or solid fence behind the border, as in the above photo? If not you should install such or plant evergreen shrubs behind, informally arranged, as well as at corners or ends to in either case form a sort of stage for the smaller plants (groundcovers and dwarf shrubs, if no herbaceous plants are to be used). In the well-designed mixed border deciduous shrubs serve primarily to form transitions between the bulkiness of evergreen kinds and the lightness of non-woody plants. Flowering climbers like clematis and roses can be trained on fences, walls or hedges, to include them in the planting, as well as large deciduous shrubs like lilacs that provide no summer interest otherwise.

In addition to the ones that Marlene gave you, some red to dark red to red-purple ones that I grow and like (and are type 3) include Mikelite, Carmencita, Kermensia, Avant-Garde, and Gravetye Beauty. Additional ones to look at include Allanah, Rosemoor, Serenata, Burning Love (AKA Vitiwester), Monte Cassino, and Voluceau. None look exactly like Niobe, and some have really different flower form, but it's worth checking them out. Photos often have different colors than the plants in reality, so if there is a nursery or public garden or a friend that has clematis you can visit, go look at them in person. Often the smaller flowered plants have huge numbers of flowers even if each flower is smaller.