Not to doom this train of thought but to my mind it makes sense.
EP350 Subwoofer
Dimensions HWD inches : 19.5" x 15" x 15"
200 Watts
EP500 Subwoofer
Dimensions HWD inches : 19.5" x 15" x 19.5"
500 Watts
What IF, as real80sman suggested, the 350 moved up to the 500's enclosure but kept it's 200 Watt Amp, that could be upgradeable to the 500's amp at a later date?
This would mean one less enclosure size for Axiom to build and a very easy upgrade path for us customers.
Consider this a pat on the back, now we can wait for reality to set in
.