mednafen is a lot more accurate than ePSXe but banning emulators wholesale with no compromise is pretty much the reason i stopped caring about GT speedrunning.
Cooper's thread explains the situation very well.
I wouldn't mind allowing emu runs if they make sure their loading times are clearly slower than console's top(or average) loading times, personally. But it's the mods call. Ideally it would be good to have a cheap option to get people's foot on the door, see if they like it, while still maintaining an incentive to use hardware.
I feel that this needs to be reexamined. The hardline stance in that thread may not be necessary anymore. The video only covers ePSXe, an emulator that's about as trustworthy as Project64. The uploader suggests that Mednafen is also inaccurate, but again it's not covered in the video, and so the description of emulator inaccuracy seems to be focused on the ePSXe testing. Additionally, this verdict was delivered about two years ago; Mednafen is not an inactive emulator by any definition, and something very likely has changed since then. ePSXe, meanwhile, has not seen an update in years, and I am told some of the newer updates are questionable anyway. I haven't even mentioned XEBRA, a possible rival to Mednafen. For what it's worth, all the PS1 accuracy tests I've found are for older versions of basically any specified emulator.
Really, people should be more concerned about different official releases or platforms that behave differently, not just emulators. Yes, they're official, but chances are that Mednafen behaves closer to an actual PS1 than a PS2 does, and that's obviously important. Different PS2s also run certain games differently, never mind the various other possible platforms... don't even get me started on that wretched Mini.
All this being said, this applies to the PS1 GTs only. Later platforms are much harder to argue for. PCSX2 is very good relatively speaking. I doubt it can be called "accurate", though it is very active (just got a major stable update) and I don't know if there's been any extensive lag/load testing been done for anything lately. GT3 and 4 also require somewhat decent PCs, especially 4. On the other hand, it's pretty much the only PS2 option, so it'd be simple enough to put it in its own little box.
Basically the same situation goes for the PSP and PPSSPP, except it does not require nearly as good of a PC to run anything. As for PS3, RPCS3 is highly experimental at the moment and I don't think it's worth talking about just yet. This is not to slight the RPCS3 devs whatsoever, it's just too early. More specifically, only HD Concept is listed as "Playable" on the site.
I don't mean to be pushy, but in the realm of PS1, we have an excellent option in Mednafen and arguably XEBRA (but good luck convincing anyone to put up with its lack of creature comforts), and these should be strongly considered... and maybe even cherished. N64 doesn't have it nearly as good as PS1 right now.
(what happened to n1nj4ofshr3d really sucks and he deserves better)