For myself I see no reason to use the XHP35 in a small flashlight. There are single 3.7 V LEDs with similar power or slightly less power but better tint on the market. The XHP35 needs four batteries or a 12 V boost driver like the H2-C (22 mm, may not fit into a Convoy S, but there will be a great new 17 mm boost driver from Schoki and Lexel soon.). The boosting losses kill any advantage of the lower losses at 12V between the driver and the LED.
The four dies of the XHP35 together are not smaller than that of single die LEDs so it will not make a thrower out of your light.
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The XHP50.2 has much more power than any single die LED but it needs two batteries or a 6 V boost driver like the H1-A (20 mm, fits into the Convoy S with some filing). The XHP50.2 peaks out at almost 5000 lm near 10 A so if your 18350 cells are not the best you can use a direct drive FET driver (like the Texas Avenger) to run it.
You will get a pocket rocket that runs crazy hot very fast and drains your batteries quickly. Without thermal control this light will self-destruct if you leave it on full power for too long.
Not a good feature for an EDC.
If you want the full power a triple or quad would give you a wider choice of LED types and tints. If you want a reliable EDC much less power may still be enough.
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Older mods with XHP50 and XHP70 suffer from holes in the beam spot. The new XHP50.2 and XHP70.2 are much better.
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In a nutshell: Both 35 and 50 (and 70) can be done, soon easier than ever. It just might not be what you really want. But who knows…