What don't you like about ported enclosures? That's a pretty blanket statement. Aren't the VMPS PR based subs? Some regard PR based subs to be "worse" than ported. At least they have higher group delay than a ported sub.
And also, keep in mind, there's not a driver on the market that will touch what Adire has come up with lately. Not SVS, not VMPS, not anybody.