Haven't seen anybody mention the LCD panel quality yet.
BITTBOY/POCKET-GO (same screen):
- High quality IPS panel - seems to be true IPS and not VA-type, judging from the BTDF. No color shifts and only a very mild brightness notch at 45/135 degrees. In panelook terms, this is a 179/179/179/179 degree viewing angle panel.
- ~2.3 inch viewable area (measured)
- TN panel, so relatively large gamma and color shifts when viewed off-axis.
- ~2.6" (LDK Game) or ~2.8" (LDK Landscape) (manufacturer specs)
Others have already covered the screen tearing / frame rate issues with the Bittboy - I can confirm these issues exist and are distracting when playing games with fast movement. My main use case for the Bittboy is playing a bunch of slow turn based stuff, so I find the beautiful panel / bad update tradeoff to be worthwhile. This is the nicest conventional LCD panel I've ever seen in a handheld. It is better than my Nintendo Switch (mid-tier VA) , better than my PSP2000/3000/Go (old mid-tier VA), and far superior to the AGS-101 screen (mid-tier TN family). The only handhelds that I own that really beat it in raw image quality are OLED devices like my first-gen Vita.
I don't have an LDK on hand to test against but my understanding is that the screen is properly updated at 60 hz v-sync. Additionally, the JZ4670(B) processor in both LDK variants is much higher performance and is currently better supported by devs than the ARM soc used in the Bittboy/Pocket-Go.
*Note: I have the bittboy and pocket-go. I do not have an LDK on hand to compare against, although I have a portrait version on the way. There are wide variations in TN panel quality, my personal scale goes from "completely unacceptable" (cheap FC handheld) to "ehh... good enough..." (Macbook Pro 2012). It is very hard to judge panel quality from pictures and youtube videos, so I'll hold off on final judgement until I have the device in my hands or somebody with access to an optics lab posts some BTDF measurements.
The obscure handhelds guy has a bit on the IPS/TN differences in feel in his latest post: https://obscurehandhelds.com/2019/07/is-the-rg300-king-of-the-jz4760b-handhelds/QUICK RUNDOWN:
Bittboy/Pocket-go - beautiful slow games
LDK - fast games