Sounds like a good solution if you ask me, to follow the aspect ratio instead. Or would it also be possible to somehow include an if-statement regarding the title screen regarding how it should be displayed? Let's say that I use the resolution of 800x540 (with dgVoovoo2's DDraw wrapper, with integer scaling for my 1080p displays). I could still fit the original Jazz2 title screen of 640x480 inside the space of 800x540 with the correct aspect ratio without stretching.

The Jazz2+ title screens that are 800x600 however would not fit the game resolution off 800x540, as the height of 540 is less than 600. That's when an if-statement could do its magic. If (titleScreenHeight > gameResHeight){titleScreenRes = stretched}else{titlrScreenRes = original};.

I don't know if anything of this is as easy as that. Maybe have an option in a *cfg-file to use original resolution on tilescreen if possible, and stretch if not possible?

I'm fine either way though. No big deal, just an observation.