Here you go
The size difference for me is quite noticeable in hand, already the sc63w feels small but does sit nicely. The sc53w if anything does not sit as nice/comfy/natural in hand, imho the sc63 or sc64 in your case makes more sense. Certainly if there is no need for a smaller/lighter flashlight(bedside duty) and could benefit from being a little larger in size(easier to grab, bigger fuel tank).
The sc63 and sc64 are very very compact as is, unless the buyer is uncomfortable with 18650 chemistry or simply prefer AA form/fuel.....................imo 18650 makes far more sense in several ways.
Why have i got a couple of AA ZL's? Well good question as i prefer the 18650 fed by a good way. Well in short i saw them for sale, thought i would try them out, the xp-l2 4000k hi cri really tempted me of the sc5c mkII(not to mention the new UI). Then the sc53w again the 4500k xp-l2 pushed me over the edge(new UI again). Then i do like the design of the sc53w over the sc5c as well.................simple as that. Right now, the sc53w is in my coat, the sc5c in my fleece.