Saga buffer stage is a simple cathode follower, so not nearly as colorful as a real gain stage.
Whether the impact is even noticable depends somewhat on the headphones used. I find it's also source dependent.
In casual testing, I find my planars (Sundara, Ananda, LCD-3f) the least sensitive to minor changes in the chain.
I spend much of my time with Senns, and all of them are far more revealing, and I quickly develop preferences.
Buffered Saga does improve headstage with both Asgard2 & Jotunheim, especially with OG Gungnir Multibit. Bifrost 4490 sees little to no benefit.
Being able to switch quickly between Gumby and Bifrost has been very entertaining. I like both, but the Velvet Sound 4490 is clearly tuned to the vinyl channel.
HD660S, HD700, HD650 sound better, to me, from Asgard2. The planars and HD800S, HD800/SDR sound fine from Jot.
I cabled up Valhalla2 briefly, and really like it with the 300 ohm Senns, especially HD800/SDR, but the buffer doesn't do much.
Mjolnir2 remains the most refined sounding in my stable, and Lyr3 the most dynamic, both cabled direct from Gungnir, and both reflect a tube roll better than Saga can, but only the upper tier cans really take good advantage.
Schiit Legos. Even olde Schiit is such good Schiit. I mean, a transparent tube pre and remote relay stepped attenuator for $200?! A pure Class-A FET headamp for $150?! Dang.