Doesn't seem like it matters in fleet arena to me.
It made Fleet easier and it's also a fun fleet to run. Anything that reduces stress and increases fun is worth it to me. I play this game for fun, after all.
That said, I stopped spending on Prof at 6* because it already kicks ass and I don't need it to do anything more than it currently does to win my matches with ease and have fun with the rebel fleet. From here there's no more spending and it will hit 7* when it hits 7*.
Also, I'm spending 50-100 on Fleet refreshes, 100-150 on Mod refreshes, 100-150 on regular energy refreshes (all on Kyros), and 300 on Cantina. It's usually the upper end (so usually 700/day) but it drops to the lower end during if I'm spending a lot on Conquest energy or a Galactic Chase or when my crystals drop below 10k (almost always because of a Galactic Chase). On top of that, I'm usually spending 50/day on 2x 25 crystal node refreshes, so 750 total in my normal budget, dipping to 600-650 when I have to worry about other expenses or a low cache.
With my purchases from other income, this keeps a good balance of the various different things I need flowing in. The one exception is Kyros. Depending on my current project, I can find myself short enough on Kyros that I'm willing to spend crystals on them (since it's cheaper than spending 100 crystals for 120 energy worth of attempts).