I'll chime in if you don't mind.
After seeing Gozer's Elf board, I'm glad I never seen or purchased that junk.
In fact I never liked any multi boards because they are too limited and seem to be shit from china. If you are going to do it, do it big. Considering the prices and such, you would want to, and avoid all the other trash out there.
I have a blue xxxx-in-1 board that is basically a PC with a Jamma board converter on it. Yes it's made in china, but it's one of the few parts that come from there worth owning. And there is an actual small community for the xxxxx-in-1 that help run this board into a good direction. Another thing, with this you can add as many games as your HD can fit, and I have about close to 3,000 games. You can also modify the PC to run a 2.8 ghz so games like MK2 and such can run smoothly. (It's a mamed PC, that is all it is) and you can mess with the configuration to set all types of resolutions, scan lines, blazy blazy. For newer games, most of the games are emulated with no difference from the original hardware. There isn't major loading time, glitches, or discoloration that I seen in the video.
Where the cons come in? Many old schoolers will complain about how many of the old games are not emulated properly for lots of different reasons. They are right. At first I really didn't see any difference other than maybe the way it looked. However after aquireing an original classic game, I found out some issues of the emulation not being 100% accurate.
I learned by playing the mame version of Wizard of Wor compared to my original mini. Some of the sounds are not emulated into the game, the wizard is missing a lot of dialog that is in the original game. Plus the music is a bit off, and the graphics look a tad worse/choppy. However that may be from me using a 24 or 25 inch monitor. Some have even complained that the sync of the controls are not 100% accurate. Tron on my SF2 cab will not surfice the original controls.
Other than that, the xxxx-in-1 offers alot, and to me the best multi-board IMHO. Now if you do get a xxxx-in-1 board, stay away from the K7000 monitors because they are very fussy with things like this. I had to get rid of mine and replaced it with a 24" computer monitor. I then went in and tweaked the setting for scan lines and resolutions and made the color settings original. Just as mame is, I have high-score saves, and a save state feature allows me to save hidden characters in UMK3. You may have to juggle some configurations on some games for the controls. That would be the final issue.