Two-octave keyboards are to me unusable. Almost every great synth melody and solo -- from Richard Wright to Thomas Dolby, from Bernie Worrell to Nick Rhodes, from Tony Banks to Richard Barbieri -- traverses more than two octaves of keyboard real estate. If you want to play more than "Bm-Bm-Bm-Bm" bass drones, and don't want to play hop skip and jump with octave shift buttons, then one needs that low F, G, A, and B note, minimum. That stated, I still cannot fathom why this rigid rule of "two octaves = mini" has become the industry standard.
Pardon my iconoclastic opinion, but I prefer either the 2 1/2 octave keyboard (ala SH-101, SH-09, CS-01, MG-1, Prodigy, MicroMoog, so forth) or three octaves of minikeys ala microKorg.
BEHRINGER Xenyx 802; CASIO Casiotone MT-70; KORG Electribe EA-1mkII, microKORG, mini-KP; QUIKLOK T20 T-REX Series X;
ROLAND Micro-CUBE; YAMAHA PSS130, PSS140; ZOOM FS-01, MRS-4B, MRT-3B
Wanted: BOSS DR-110; CASIO CZ-101; YAMAHA CS-01, DX-100