Fellow biker here (generally mountain biking now, but I’ve done some backpacking trips). Maybe some of what I’ve sorted through can help. I also own a Convoy 2.1A S2 and some Convoy M1’s (built for helmet use). I’ve posted some beamshots comparing some of the typical optics beams. I’ve also tested some diffusion techniques (though don’t trust the lux comparisons so much - that’s before I built my sphere).
From my limited experience I’d say in this order choose a headlight, then a headlight, then a headlight 
. Seriously, the headlight will be worth it’s weight in gold when you need both hands. Go neutral white (4000 to 4200k my personal preference) whenever possible; while biking you’ll get less glare and be able to see details such as rocks, roots, etc. . . much better. I’d also recommend quality lights. The Convoy’s are a value that is extremely hard to beat. Problem with Convoy’s has been the usual stock “2 group” driver which has that annoying flash in low mode and is too easily accidentally changed into the group with flashy modes.
I do like your idea of using a flood-to-throw light. You’re never going to beat the wide flood of a zoom light with a reflector based or TIR based light. It’s versatile too. I would look at the cheap Warsun X65 (I have one which hasn’t been used much) which takes 3*AA’s * not 3AAA’s like listed at Banggood. AA’s will give a huge runtime increase over AAA’s, though at the expense of weight and size (that Warsun is very large).
On my trip (not that long of a trip) I fretted too much about being able to get batteries on the go. In reality the numerous 18650’s I carried (in cases) were way more than enough for me. I’d say carry more cells and buy some good high capacity ones to get the most runtime.
I agree with the post above, you need more throw for riding with speed. The S2 would be sufficient at slow speeds, but I’d step up to an M1 for faster rides. I’d say the M1 has enough spill for rides on road or path, a bit too dim of spill for me on singletrack in the woods though. See this thread on my 2 Convoy M1’s (XP-G2 @ 2.1A vs. XM-L2 @ 3.04A). I’ve since reflashed the drivers to boost low mode up to 30% (or was it 35?), but it’s still 2 mode, always starts in low. Surprisingly 30 (or 35, whichever it is now) isn’t that much different in actual use from 100, but has much much more runtime.
-Garry