Evil and Chaos wrote:
3x Phoenix Bombers - 400-pts
Void Spinner - 250pts
...
What am I missing, when I look at them and say "that's the choice of a loser" and you say "I can't see someone not doing well with these" ?
Most importantly, your firepower comparison is off. The sustain fire bonus will not come close to making up for the direct fire shots on the bombers. The bombers are throwing out 9 shots at 4+ each, or 27 pips. Sustain fire is +1 to-hit pip per target under the barrage. Obviously, that's not going to be in the same ballpark, regardless of conditions.
If you figure something like a mounted infantry unit, using vehicles for cover, but spreading out to avoid barrages, that's maybe 6 targets under a template hitting at 4+ (AV or infantry/cover) on sustained fire, that's only 3 hits. The Phoenixes would hit the same 6 targets at 5+ for the barrage, plus 6 AT4+ and 3 AP5+ (infantry/cover), that's 6 hits on average - double. The only reasonable comparison that is any better for the Voidspinner than that is a pure AV-in-the-open target, in which case the difference is only 3-5.
Big difference in favor of the bombers.
There are some other minor effects as well. The first one that pops to mind is that staying loaded in transports can provide effective barrage defense. When the barrage is accompanied by high quality AT fire that specifically targets the transports, that goes away. That makes the Phoenixes a little better at pressuring forces to spread out and slow down.
Another is that I'd say, overall, the bombers are more durable as an activation because for an opponent that can bring something to bear, a Void Spinner is pretty fragile. That's just a gut feeling, though. It would be nearly impossible to theory-hammer and it would take a ridiculous number of batreps to really see if that's true.
I don't necessarily think those factors make up for the full price difference, but they count for something.