re: Got my NES RGB modded and it is incredible

I've done lag tests for my setup before by hooking an SNES to my Sony BVM's RGB input, then daisy-chaining the Framemeister to the BVM's RGB output. I then ran 240p Test Suite for SNES off of my sd2snes cartridge. It displays a test pattern with a timer on it, so you can take a photograph with a camera and then look at the photograph to see the time differential between the CRT's display and the flat panel HDTV's display. That differential will be the total lag time for the whole video chain (Framemeister processing + TV panel's processing). However I've only ever used it with low-lag Samsung and Vizio panels in game mode.

The Framemeister adds a few ms of lag. You will not notice it unless you're used to gaming on CRT monitors. If you are used to gaming on CRT monitors, then you will probably notice.

1) I play a lot of speedrunning on my favorite old platformers like SMB3 and SMW. Playing on a CRT has much better handling when I'm making split second nearly frame perfect button presses. But if I just spend a few minutes warming up on the Framemeister, I can probably play almost as well.

2) The example I always use is Mike Tyson's Punch-Out for NES. For those unfamiliar, each boxer you play against has a pattern, and they telegraph their next moves by small visual cues. You have to identify the cues and react extremely quickly. It's a notoriously unforgiving difficult game. On a CRT, I can pretty much easily get all the way to Mike Tyson before he hands my arse to me (never have I beaten him). But on the Framemeister, I find it extremely difficult to get to Mike Tyson, and I have to really sit there and focus and work at it to make it that far. The lag just gives you such a small tiny window to react.

The other issues with the Framemeister vs. a real CRT:
A) Light gun games are still off the table. It's not the end of the world, but you leave behind some real gaming classics
B) A lot of games in the PSX/N64 era switch between 480i and 240p throughout the game. On a CRT this was no problem, there was no processor that needed to re-sync to the video signal. It just worked. On Framemeister, it needs a few seconds to re-sync. So on a game like Resident Evil 2 for N64, where the action of the game is in 480i but the menus are 240p (or vice versa, can't remember), you have to wait 3-5 seconds to see the pause menu and then wait another 3-5 seconds after the action resumes (in which case you very well may already be dead).

OSSC is practically lagless, but because there's no framebuffer, compatibility with TVs is not guaranteed.

So no matter whether you go with Framemeister, OSSC, or a real CRT, there are some concessions to be made somewhere, no solution is perfect. And that's how I blew way too much money on just buying every solution instead of picking a compromise