if your server is still using tobi it is difficult to make a successful team with sailor in it, and by successful I mean being competitive against players ~2k around your power, not by overpowering them. my opinion is that sailor is a great ninja to have, but not right now with ignite running everywhere and ninjas getting 1 shot left and right. this is based on my experience (I'm not from one of the oldest servers where the meta has evolved past 1shotting in turn 2, so sailor doesn't work).

In my opinion, after you have reached above 25k power where your summon runes are likely above level 4-5s and magatamas almost all level 4s, you stop getting much utility from lucky dice. It is still the cheapest event if you NEED a ninja from the event as you can consider the extras as "rebates", but if you don't need it, it is an expensive money sink to go out of your way to get it. Above a certain power level, you are better off saving for treasure of the sages and get specific stuff u need from discounts.

will sailor and/or getting sage jiraiya 4 str change your gameplay? most likely not. don't buy things now you don't need. ninjas will likely come back so very often. get them when you need.