For science! This is the ~$80 Retro-Bit Super Retro Trio 3 Plus testing the AV output with a ~$300 Retrotink 5x Pro upscaler. Actual NES carts!
The lag or latency is near zero, all feels like an original console to me. The biggest downside as you can hear (literally!) is the Dendy NES on a chip being used is terrible for audio, and the sound effects in particular in NES games do not sound correct. Listen to the 'coin' or 'jump' sounds in Super Mario Bros, for perhaps the best example.
This console does output both composite and HDMI simultaneously which could be of great use for CRT play + HDMI capture.
I purchased this from Amazon (March 2023) and there is a 4:3 / 16:9 switch on the unit. I believe past youtube reviews stated this was a missing feature. Retro-Bit must have added this at some point recently. The model number on the bottom states: 22L30QL
00:00 Ninja Gaiden II
00:30 Journey to Silius
01:07 Teenage Mutant Ninja Turtles
01:47 Super Mario Bros.
02:32 Mega Man 2
03:17 Castlevania III
04:12 Astyanax
04:43 Spy Hunter
05:23 Super Mario Bros. 3
06:03 Batman