Admiral Toad wrote:A while ago Richard at wineworks said they were going to launch one but to fit the original lid
That looks more elaborate And expensive
Eeee it's like trying to spot motorbike prototypes on test rides

In reading both the SS and MJ FB posts, they also appear to be testing a mash tun as part of a push for all grain spirit making which is a good thing for hobbyists wanting to go beyond essences.
I am still using my old SS super reflux boiler in combination with the original lid but fitted with a 2" ferrule. With this set up, a sugar wash will run fine. However, a whisky or rum wash will render it susceptible to puking because of the lack of head space. This can be mitigated by reducing the volume; but, the run becomes less efficient. (I am planning to remedy this by getting a 15 gallon Brewhaus boiler.)
This onion dome head appears to be designed to address this problem. I do see the potential for out-of-round. I would imagine it has been engineered with grooves and gasketing to snug back into round once clamped.
Cheers!