It's worth doing this just to see the menu.
Unfortunately no.

Vanilla Clouds of Xeen also had a beautiful menu.

I didn't know that. I originally played vanilla Clouds of Xeen, then added Darkside later to tackle that. I wonder if I will find the beginning too easy when I play it again as World of Xeen. Then again, I do remember the early game being the hardest part.

I thought it was possible to go from World to Clouds (IV), with a similar process as going to Darkside (V). However, it doesn't work. Darkside and World use the same EXE -- Clouds has a different EXE.

Does it work with this exe (change *.jpg to *.exe)?

Almost :-)
You will need the Clouds EXE as well as XEEN.DAT from the Clouds version. XEEN.DAT is an executable that does most of the work for Xeen. With the EXE you sent, you get the Clouds intro .... then the WoX menu.

I was thinking of modifying the Clouds EXE to look for CLOUDS.DAT and CLOUDS.CC (both renamed) as opposed to XEEN.DAT and XEEN.CC -- in theory you could then run Clouds and Darkside side-by-side. It seems like a lot of trouble just to see a different intro....

Xeen.dat here (also need to rename from jpg to dat).

Does it work now?

A few questions about the experience bonus:
Does it apply on both sides or just Clouds?
Does it apply just to enemy experience or to event experience as well?
Do temporary levels affect this bonus?
Can you keep getting the bonus by deliberately not leveling up past 14?

If it applies to event experience, then clearing Dragon Tower at level 14 or earlier could give everyone 40 million experience, which is rather absurd. That combined with all the other experience you're getting is more than enough to level up your party to 50.

It applies to both sides. Only experience from combat is doubled. When you get factual lv15, you lose EXP bonus.

There is not much use of it on Clouds though - best training grounds can increase your level only to 20, but before that you are usually 1-2 levels higher than what you'd be without XP bonus (which is a huge difference at low levels in MM4-5 ruleset)

Perhaps this buff was made to compensate for Darkside's difficulty spike (-> Armadillos' road) and lack of lv5 party (starting party level in MM5) in case players will want to do Darkside first. Tbh, experience isn't really limited in Clouds of Xeen at all. Warzone monsters give EXP, vampire town seems to be subject to respawn and there are machines which keep producing monsters (EXP) in Lord Xeen's Castle.

Even then, if I go to the northwest corner ofDarkside at level 14 or less, that is an extra million EXP (divided by the number of party members) per Gamma Gazer, and a million per Annihilator/Autobot. Killing those at level 14 is doable if you use the fountains and have enough gems to keep casting spells. For Gamma Gazers, use Mass Distortions followed by Implosion/Star Burst, and in Castle Alamar, just keep throwing Implosions. In other words, this can still be exploited for a lot of extra experience.

Yep, replacing XEEN.EXE and XEEN.DAT with the versions you posted gives you Clouds-only. I haven't verified beyond the intro, logo, and starting a new game.