no brand baths are a lot easier to deal with from the consumers point of view, and not as important to be branded (although quality is always important) as you pointed out, no tap holes yet, so as long as the bath is of reasonable build quality, the only thing you might struggle with later is a replacement panel.
showers on the other hand, may need a ceramic valve from time to time, or other bits and pieces, so it's always prudent to get a named brand one.
like i said, grohe and hansgrohe do those fill/waste things, showerlux do a version too i believe, that actually fills from the plug hole (or at least i think it was them... someone does !) ... and yes, grohe and hansgrohe are actually different companies (i think there is a third too, called friedrich grohe unless they are the same as grohe) Villeroy & Boch might make one, but it will be expensive if they do, and have a look over the ideal standard website too