I’ve got the same copper SST-20 4000K bundle sitting in my cart, trying to decide whether to hold out for the Ti/Cu. I’m leaning towards just getting the plain copper now.
My biggest concern with all titanium is whether the pill can take the heat. If it gets too hot in there the bondwires might desolder themselves from the star. However, the thermal sensor on the driver should protect against this. Hopefully. I never had any problems with overheating on my pure Ti FW3A so the FWAA should probably be fine.
For pure copper my concern is a bit different. The copper might transmit the heat just a bit too well. Sure it can probably run on turbo longer… but the entire light will heat up at a similar rate leaving no safe place to hold the light. You might need an oven mitt to run it on turbo.
Ti-Cu might be the sweet spot. Good heat conduction from the star, while the back end of the Titanium body tube stays cool so you can actually hold the thing when the head gets hot.
Once the metal is saturated there is little difference between copper and aluminium. Copper might absorb the heat faster but aluminium emits the heat faster
IF they are using the same batch as they have done in the alu versions, then it’s very nice indeed. I got the 3000k and 4000k in those, and I’ve ordered the Cu-Ti with st-20 4000k hoping for a good tint and a touch more throw