I have wondered the same thing. I have been taught initially to place the tip of the tongue where the ridge plateaus off into my cavernous HIGH palate lol. Upon discovering this website, I see that some people put their tongue almost right behind their teeth! I am trying it because it seems to allow my posterior part of the tongue to have space.

This is an interesting new article, I'm going to speak to some myofunctional therapists about this. Keeping the tip on the incisive pupillae is what Mew recommends, I wonder what led him to this conclusion. Perhaps there are separate schools of thought among myofunctional therapists - since he used to recommend people to them I would assume he has gotten information about tongue position from them.

Right now my recommendation is to experiment with both! 

It depends.

My forward growth isn't terrible (45 mm from bottom of front teeth to tip of nose) but then again I have being mewing since November 2017.

I can say as someone who used to have a class 3 I don't want to go back to prognathism again so I like my new flat profile given to me by orthodontics.

However I knew they narrowed my lower palate to make it fit my already narrower upper palate. 

This in turn caused my jaw to sit back too much as my front teeth were tipped back with elastics. I think this made my maxilla come back even more as I have bad bad scleral show.

But at this point it seems my maxilla has come forward and I never ever put my tongue near the tip. I suction it to the top and it lands BEHIND the rugae not beneath them like this site claims.

However I think going beneath the rugae and behind the incisive papilla  might benefit people whose teeth are tipped inwards too much.

When I had a class 3 I had my teeth tipped  outwards. It created a strong chin but it made me look primitive. 

However I think when my tongue can be suctioned effectively I may go beneath my rugae. My problem though seems to be only slightly lacking in forward growth and more so lacking side growth. If I expand my maxilla more, my mandible is free to jut forward more to have a stronger jawline with a lessened gonial angle. This means my already strong chin (which points down) will point FORWARD since the mandible has more room for movement to bite down properly. 

If my teeth tip a bit forward I wouldn't mind. I think this gives the lips great support and also allows the mandible to jut.

My fear is that at the moment my maxilla needs more width and my natural suction goes to the high palate. 

If I get to 42mm from upper incisor to nose tip I may have a brand new posture anyway. Who knows. But expanding OUT is necessary for me. My forward growth i don't think is too weak. I have seen people with way worse forward growth than mine. I doubt anyone would give me a LeFort 1 at this point. 

My issue is side growth. If I get that I can move my mandible to its rightful place. I think my jaw position would cause a gentle pressure on my incisors to tip anyway since the orthodontics purposely gave me a stupid deep bite aka an almost overbite. Front teeth don't really touch at least not properly. So it just keeps my front teeth tipped back which makes my mandible sink in. I know my "not so deficient" forward growth accounts for this. I know I am recessed but not horrible. 

Tl; Dr: it depends