no, with +2s is not worth. Used to be worth with the +4 that came from old brothers farewell tis. But i think we are close to the introduction of kage TI whose hard mode tools drop +3 and +4 like the old pre UT introduction BF, so, at that point, you could think about doing it.

yes, but those resistances reduce only the effects where is stated that are elemental based and they are useless against full tai effects (and to get all +20% now, differently from the old times, when +4 resistances were available, you need to give up on a too high quantity of damage reduction, resistance, defense, critical, injury, hp on the tools to be worth the effort).

What i mean when i say this?

Example:

this effect gets reduced by an enemy resistance to water

but this one doesn't get reduced by an enemy resistance to lightning even if the ninja that uses it, mabui, is lightning based.

The same goes for half nin half tai effects.

this one gets reduced by the enemy elemental resistance to wind

but this one no, even if is landed by a wind ninja (kushina).

So, don't overvalue the effect of those resistances. They are situational.