README: v4-600 vs v1-850 decision tree (4-step heavy motion caveat)

README.md

@@ -18,24 +18,37 @@ joint **video + synchronized stereo audio** in as few as **4 sampling steps**
 instead of the usual ~20 — a ~5× sampling speedup — and keeps getting better as
 you add steps.
 
-## Current best — `v4` at step 600 (EMA)
+## Which checkpoint — `v4` (step 600) or `v1` (850)?
 
-**Download `minimax_h3_turbo_v4_step600_ema.safetensors`.** It's the strongest
-checkpoint we've released:
+For **most** work, use **`minimax_h3_turbo_v4_step600_ema.safetensors`**. It's the
+strongest checkpoint we've released: much better static and small-motion shots,
+markedly better micro-detail (faces, fingers, fine texture), and the
+over-sharpening / plastic look of the earlier `v1` (~850) line is **fully
+resolved**.
 
-- **Static and small-motion shots** are much improved — clean, stable, natural.
-- **Micro-detail** (faces, fingers, fine texture) is markedly better.
-- The **over-sharpening / plastic look** of the earlier `v1` (~850) line is
-  **fully resolved**.
+v4 introduced a **static-frame enhancement** — a big win for static and
+small-motion content. The one trade-off shows up **only at 4 steps with large,
+fast motion**, where v4 can produce **motion-smear / trailing ghosting** (we're
+actively fixing this). Two things address it:
 
-Two things still fall short of where we want them, and are what we're working on
-next:
+- **Use 6–8 steps.** This **largely removes the smear** and is where v4 looks its
+  best. v4 also tolerates higher step counts better than v1, which tends to
+  over-sharpen at high steps + strength 1.0.
+- For the specific case of **4 steps *and* heavy motion**, the older **`v1` ~850**
+  checkpoint can still be the friendlier pick.
 
-- **audio** quality and consistency;
-- **behaviour under fast, intense motion**.
+```
+Using 6–8 steps?        ── yes ──►  v4-600  (recommended)
+   │ no (4 steps)
+   ▼
+Heavy / fast motion?    ── no  ──►  v4-600  (recommended)
+   │ yes
+   ▼
+                                    v1-850  (friendlier at 4-step heavy motion)
+```
 
-Everything else is in good shape. It's still a preview — training is ongoing — but
-a considerably stronger one than the earlier rounds.
+Still a preview — training continues; the two areas still being improved are
+**audio** and **behaviour under fast, intense motion**.
 
 ## Steps and strength — read this
 
@@ -93,7 +106,7 @@ EMA files**; the non-EMA ones are for comparison.
 | **`minimax_h3_turbo_v4_step600_ema.safetensors`** | **recommended — current best.** Strong static/small-motion, good micro-detail, no over-sharpening. |
 | `minimax_h3_turbo_v4_step600.safetensors` | v4-600 non-EMA (comparison). |
 | `minimax_h3_turbo_v4_step150_ema.safetensors` | earlier v4 checkpoint. |
-| `minimax_h3_turbo_4step_ema_ckpt850.safetensors` | `v1` line (~850) — sharp but over-sharpened / plastic; **superseded by v4**. |
+| `minimax_h3_turbo_4step_ema_ckpt850.safetensors` | `v1` line (~850) — over-sharpened / plastic in general, but the friendlier pick for **4-step heavy motion** (see above). |
 | `minimax_h3_turbo_4step_ema_ckpt500.safetensors` | older `v1` (~500), softer. |
 | `minimax_h3_turbo_4step_ema.safetensors` | initial release (~200). |