Hi Chipdouglas, I just bort an RRT-2 R5 last week, then a TC-R2 this week.
The TC-R2 is really a single battery pocket sized RRT-0 in titanium.
My RRT-2 R5 is rated at 300 lumens, similar to your wishful RRT-1 R5 @ 313 lumens.
My new TC-R2 S2 is rated at 310 lumens! Fractionally brighter.
However, lumens only indicates the total amount of light emitted.
Next to each other, the twin battery RRT-2 is significantly brighter in hot spot and more tightly controlled than the pocket sized single battery TC-R2.
The RRT-2 is significantly a better thrower of the two; really a mid-distance tool only.
The TC-R2 is floodier, practical for short distances.
Thus, your question of RRT-1 R5 with big 48mm diameter, versus Jet III M R5 with only 33mm diameter; both twin battery.
The Jet III M is really a compact, and probably designed for military with a simple tail end clicky switch only, and no magnetic ring; you will be pushed to hold the flashlight by either the overhand grip, or the loose cigar grip to operate the tail end switch.
The smaller reflector won't be able to control the sideways spill despite the 355 lumens, so it probably won't throw as far, but it will be floodier.
The RRT-1 with it's wide and deep [longer] 48mm head will control the sideways spill and throw far, but it will be less floody up close a few meters away; the RRT-1 also has a nice practical magnetic ring control - esp useful if you wish to use the lazy underhand handshake grip.
Hard to say who is better overall - depends on your needs.
RRT-3 for medium size head and long thrower.
Jet III M for small-medium head, and floodier throw...
Decent spill and awesome throw? Get the bigger deeper reflector RRT-1 anyday.
Don't worry too much about the Jet III M's extra 42 lumens...
