I have a bunch of Brian's DT's, some he custom made for me, but all bought between 1-2 years ago when he didn't offer wide bores. Have not used any of them though since my 'Vari days abruptly ended over a year ago. You can't ask for a better person to deal with, and fast customer service is the norm from Brian. Even the custom tips shipped the same day or next when I ordered them.
Have lots of big bore tips, but so far have just run the tips that came on the Chalice II and III's. I get all my big bore tips from Synervape now days (he offers black or white Delrin, SS, naval brass or copper in many designs, and will custom build to your specs for the same $10 each shipped price). I have some friction fit black Delrin from Michael just like the tapered stubby Train pictured above (and straight grooved shorty's as well), so may try one on one of my III's just for S&G. He offers the BillowPro Delrins with a tapered, straight or straight grooved profile, in stubby, short and long. His CloudMaster metal tips in similar designs/lengths have either a standard big bore or 1.5X big bore. He is another great person to deal with, and his customer service is like Brian's.