As Joe and Isaac are saying, I think speaker power ratings are subjective at best, and like power amps the ratings can be pretty much whatever the manufacturer decides to use as their rating criteria.
I've never seen an amp rated for more output than its power consumption though, but I rarely look for consumption ratings except with modern multi-amp megawatt sound systems in old venues.
In the early 90's I regularly ran an amp rated at 600 watts per side @ 4 ohms (Carver PM 1.5) into Hartke 410XL and 215XL sub module cabs, x’ed at 85 hz, both 4 ohm and rated at 400 watts.
No problems, and I would run my rig very hard at outdoor venues, sometimes 4 to 6 times a week in a stupidly loud, but lucrative alternative band.
I have better luck with more power rather than less, if I was were using a 200 watt amp at those levels I'd be clipping constantly and no doubt would have toasted some drivers.
