Either pinestraw or a heavier, chunkier mulch will help with the erosion.

I have mondo trying to push up pavers and growing up through the cracks; I doubt any mulch will be a long term impediment. Since your plants are new, though, I would be careful not to cover them up.

Thank you I appreciate any and all suggestions.

In this situation I would use a finely mulched medium, dried leaves or pinestraw being one of the best. It won't impead growth of the mondo, but will help prevent erosion until it gets established, although heavy rainfall will make folly of even the best laid plans.

Good luck - you have a great plan by using dwarf mondo, which I like; it'll just take a little time to become effective. Let us know of the outcome.

More people should discover dwarf mondo.

You might want to spread some pre-emergent herbicide (eg., Preen) regularly to discourage weeds while you wait for the mondo to fill in. Otherwise, weeding that big an area by hand will drive you nuts and mulch won't completely prevent them.