My dream has come true
I'm super happy right now having both Omegamon and KaiserGreymon as my partner.
I knew DNA evolving will devolve one of my partner back into Ultimate. So I thought might as well have ShineGreymon to fill up the field guide. When I was training my MetalGreymon to get some extra Wis and Spd, an evolution requirement unlock after a praise and it was KaiserGreymon. I never knew; now I want it and I got it. He's super cool; he actually uses his sword in his attacking animation and his finishing move animation is just godly. He even does Cloud's spinning sword victory pose lol. Now I just need to finish the game with them and I'm all set with my training and preparations though I'll only be able to do it next week as I'm back to work again which is tearing me apart ;_;
Interestingly, Omegamon is actually classified as a higher stage compared to Mega; a Super Mega I guess. You can see that his Mega designation is golden colored compared to KaiserGreymon.
What's interesting about this is that your other Mega actually receives extra stat boosts when training because Mega is a lower stage compared to Super Mega. My KaiserGreymon is actually gaining double of what Omegamon gets because of this though their stats is still so far apart as Omegamon got some nice stats boost after evolving. Although there's a big downside with Super Mega in that you cannot use ExE evolution with them. On the upside, they are ridiculously powerful and more reliable than ExE evolving which can only be manually used once a day or resetting for an afterdeath ExE.
Unfortunately, I'm guessing that my Omegamon life span doesn't reset while the devolved digimon does; which means my Omegamon's age is still 13 while my MetalGreymon resets back to age 7 after DNA. I'm afraid that my digimon cycle will be out of whack because of the possibility that Omegamon dies first. So I transfered my MetalGreymon's life to Omegamon everyday hoping that they will be in sync in the end. But if Omegamon does get increased life span because of DNA then KaiserGreymon will die first which is unfortunate. If that happen, I'll just transfer Omegamon's live to the new digimon to resync, hopefully.
So now it's an interesting choice between DNA evolving early or late. DNA early and they will last longer but they are weaker since the lower stats equates to lower boost when evolving. DNA late to train first will yield a more powerful digimon but you will have less days to make use of him. Since evolving the devolved Ultimate will take up 4 days, I'm not sure if it's wise to DNA at age 18 and up since they will be within 4-5 days of dying. At the end of the day, I don't know if DNA evolving extend a digimon life or if it does, for how long. As I'm unable to play the game until next weekend, I couldn't test it myself so this is just speculations. I hope that this will help for those that are curious about DNA evolving.