somehow, if i read correctly, it doesn't seem TS is concern about budget, he's more concern about m43 (OMD) capability to cover events and for travel, if that's the case, would say yes, OMD is capable (IQ & low ISO) enough. There's quite a few excellent lenses now, most complete amongst mirrorless, additional battery grip for functions, and flash options. though OMD would not match C-AF of DSLR, Single-AF is very good though, matching DSLR. You can even use OMD+prime as backup to D90+17-50 for events, won't break you neck certainly with it. Of course if budget constrain, stick with nikon