I'm on the mission for large to XL tips also. Don't have the DM6 yet, it's in the mail, but I have been top rolling quite a bit with my DMG and other iems.
The large Symbio W Peeled were the first tip I thought fit. Largely, I think this true because even though the tip is a large, it's silicone is a little stiffer so it seals a bit better than normal large tips. I think this is why people think they are a size up, but actually is the stiffness of the silicone that gives a "larger" impression and hence the feedback on that they feel great at first but are fatiguing.
New Bees large tips are very similar in size and shape to Symbio W Peeled but with softer silicone and they do feel more comfortable but with a bit less seal. These are ok for bullet type IEMs but I need larger ones for universal ciems.
On a whim, I ordered JVC Spiral Dot L having owned the ML size and they are larger than Symbio W Peeled and softer. The sound bore is huge though so for hot iems, they are unforgiving. I like everything about them though. I wish they sold an exact second version with a slightly smaller sound bore. They seal great.
Moving on, I ordered the Sony EP-EX11 Size LL tips and they are great also with a smaller sound bore than the JVC Spiral Dots. They tame the highs a tad, seal well and are comfortable.
Both the JVC and Sony seal better with more comfort than the Symbio W.
I also ordered the Sony MH755 and the large top included is somewhere between the JVC/EP-EX11-LL and Symbio W in size with better comfort than the Symbio W and a smaller sound bore than all tips mentioned. More attenuation of the highs than the EP-EX11 tips.
I'm still looking for the perfect tip and didn't know I had such big ear canals but the seal is critical!
On another note, I'm not sure I shove the tips in as deep as others, but the tips mentioned provide a great seal. Perhaps if I shoved the iems in deeper, I might get away with smaller tips, who knows. This is my latest curiosity but with the larger tips, the sound is better, they are comfortable and I feel the entire experience is better. I'm also not sure how deep is safe to push an iem into ones ear.