I mean SW1-HL2-Barb3-Doppel3 is a decent build if you insist on having Barb3. HL2 gives you a bit more active skills to use as filler + the crit attack passive.
However, that said, Shinobi is just straight up busted right now. Cloning lower rank class attacks gives them higher multipliers than even Rank 8 class skills. It’s partially why Murmnobi is such a powerhouse. The reason Shinobi wasn’t that effective with Doppel in Rank 8 is because you can only get up to Doppel C2 if you include Shinobi. Doppel C3 is a huge power spike - I mean Zornhau literally hits more than 4x as hard in C3 compared to C2. Similarly with Redel and Zucken. You also get Zwerchhau only at C3, which is a +80% slash damage buff on non-plate enemies. There’s Punish-Earthquake for the AoE cheese - but that’s about to get fixed. With rank 9, you can combine the burst of the Shinobi with the burst of Doppel C3. We’ll see if it can compete with Mememillo.
But, all this is purely academic if they decide to nerf Shinobi.