Thinking about Minolta 28-70 F2.8 G, went with TAMRON SP 28-75mm F/2.8 XR Di LD

Neither is an F2.8 lens. The CZ is only half a stop down in speed at the wide and just over a stop at the long end compared to the 28/70 F2.8. If you want fast you need to be talking F2 at least but preferably F1.4 with lenses like the new Sigma 35mm, Sony 50mm 1.4 and CZ 85 F1.4.

I think build quality ceased to be an issue a while ago. Mine is absolutely fine and suffers no mechanical problems. It might be light compared to a 28/70 but I wouldn't call it small . I suppose that depends on your frame of reference. I come from an Olypmus film background and those old Zuiko lenses were small.

Mind you I wouldn't want a 28/70 on aps-c anyway.  Just not wide enough for a standard zoom with 42mm equivalent at the wide end.  The CZ 24-70 is just about OK as that roughly 36mm equivalent wide end is a lot  more useful but that is very heavy and very expensive.