Good to see you here Vinh! Like your S2+ mods - I always use NO-OX-ID as well. One tub from Illumn has lasted me for years. I'm lik'n the VTC5D's (Vapcell branded) or the Samsung 25S's lately.
Have you seen loneoceans' FET based switch with batt voltage monitoring LED's for the S2+? Incredible! I only recently saw it here: https://budgetlightforum.com/t/-/50404
Also might want to check out his boost driver here: https://budgetlightforum.com/t/-/50015, also quite an incredible design, getting 50 watts from a single cell.