So I couldn't find any solid details on the motobecane 400/500/600 series frames. So I figured Id post once I found out.

Semi-confirmed that kenesis builds the HT series frames, out of straight 7005 aluminum (no butting). The different models are identical except for V brake studs vs. disk mounts, and mechanical vs hydraulic brake cable routing facilities.

Having owned a 550HT, I picked up a 450HT frame from bike island for my new sram x7/x9 build. The 19.5" frame weighs in at 2000 grams exactly, with seatpost clamp. That 4.409 lbs (4lb 6.5 oz). That's less than half a pound difference between the HT series and the fantom fly. I cant exactly measure strength side by side, but I don't suspect the butting gains you much for strength, though the kenesium alloy may be beneficial in this area.

I know I'm late to the game now that the HT series 26ers are being discontinued, but I figured I'd post my findings just the same. Ill try and get all up weights for the stock 550HT as well as my new build once its complete.