Truthfully, I think it is a good idea but there must be a progression. By this, I mean start wit normal demension hoppings, aka going to the next one over and such then eventually leading up to being to jump to the marvel verse. So like within dc at first then eventually bridge the gap between marvel and dc. At the same time, some people might take things way out of whack, like creating 87 different versions of their characters. I should know, I have backup bios of 5 different Antics. But there should be a restraint on how many come to the verse of a certain character. Otherwise, you can get paradoxes and weird team-ups.