I have a lot of grape hyacinth. These were high quality, deep purple varieties from Scheeper's bulbs. They've been in a year and look very healthy.

No, it's not invasive, though the clumps did get bigger. Most of all, I didn't realize that unlike daffodils, grape hyacinths foilage stays green much of the year. I wanted to underplant bushes, this would be better mixed with other plants where you hide the foilage in the summer. It would be stunning in a mass planting of day lillies, daffodils and graph hyacynths. I have enough that you could do a fairly large planting like this.