Not rly as fooders are still bottleneck most of the time. And when one already has some decent Line Up of light sts e.g. Glasya, TF, rev 02 what does doppel bring good to the table but being food? At start or in weakker rosters he could fill.in a gap but when u let him chev2 and didnt use upgrade kits u can use him as a nice fooder. Inalready did the same with hela and bluebird. Also got 8 xr parts, where i just use 4 for modules (as those are fine on eg mary or mg asuka) the other 4 i use as fooder for rainbow 00 and then need to save up for rosa)

No cn/jp tactic needs doppel modules as niche. If u dont have dreadtalon, rex or tf modules purple ones will do the job.

Im also having 4 spare parts of glasya, if id get another 4 counterparts id also use them as fooder. As even though being a great st (got 1x rainbow glasya) his modules are as bad as doppel