@Pulptenks SuGu was an extremely broken build during the dark days of episode 4 which no summoner main actually misses in any serious manner. Shit was so broken it would literally 1 shot 12 man magatsu on XH, cause weird buggy phase skips due to overkill damage on other bosses, etc. Maron built even faster than it does now, chain trigger bonuses weren't mainclass only (which also caused Br/Gu to happen which was a build also so broken SEGA literally threatened bans over it, and it caused Magatsu to be 4 run limit), and you could build chain trigger with uncharged techs. Shit was broken as hell and never deserves to come back, it would just make our damage on JP even in current ep6 patch look pathetic.
SuBr is really basic build, lower damage than SuFi but can use a dex mag. Which is cool and all, but Phantom is literally at least 4 months away. You only need 1000 excubes + whatever amount of devices/discs to fully change a pure 200 non-dex mag into a dex mag so even as a free to play player, you should be able to do this -- especially because by then, PD Solo Triggers which drop 40-ish excubes of 10 star weapons per run should be in the game and easily accessible through some sort of badges. The big thing about SuBr is it has good autoattack damage but yeah... That's not exactly something you want to do much. Good memes for afk boss attempts with Viola or Rappy though.
The phantom tree as a subclass actually only takes 40-ish points because thats all you can take from phantom as a sub, everything else is mainclass only. You get good multis, your support techs lose no damage while charging even faster and for cheaper (seriously, I miss having less than 30 pp cost resta), and you get anywhere from 40-60% crit allowing you to crit cap your pets (phantom also gives crit damage too) which means Lethal Parfaits (deadly parfaits on JP) with their 10% crit dmg become hard to beat. You also get 20 pp from phantom as well, AND you move faster while charging techs too. You also have a small bit of extra pp regen per second, and your autoattacks restore more pp. I think technically speaking, SuFi can do higher dmg, but it's not consistent and SuPh's utility is far too strong.
That said my TL;DR:
If you really are scared of spending 1k excubes in 4 months to fix a mag, just go tech SuFi and then slowly work it to the slightly more optimal dex when phantom comes out. Tech is the same damage as dex if you're crit capped but dex has other benefits like lowering the max dmg you can take. That said, 1k excubes in 4 months time should be a joke.
As for defensives, Br doesn't help at all compared to Fi so I don't get that. And dying a lot with alter ego? You have Dia Master 5/5 on summoner otherwise it's not truly a summoner build, that skill is insanely core. It's like playing knuckles fighter without the gear skills, or dual blades bouncer without the db break stance skill, etc.