I'm not sure it could be worse than Gane given what I just saw the striker Volkov do to Gane...but I do agree that it's at least mostly untested. And no I don't think he's Werdum off his back if he is taken down. I do think he's eons better than Gane overall with his grappling, and likely worlds better than Stipe off his back.
The question isn't "Is Aspinall an absolutely elite grappler" because my honest answer would be "probably not". The question to me is "Given his other physical advantages (younger, faster, bigger, more explosive), is Aspinall's grappling at least good enough to survive that world (be it via TDD, getups, threatening with subs to allow him to scramble up, etc) and have the fight mainly where he wants it?" And to that my answer would be "Probably", given what Jones looked like to me in his last fight.
No guarantees obviously. Just how I see it.