Repotting Milts

[orchidsinstl]

For those who have experience growing and repotting milts - I am repotting my first miltoniopsis and have a question about how much to size up. The plant is in a 4" pot, but it has grown so vigorously, the roots have actually split the pot. If I try to allow for one year's growth, as I would with a cattleya, would I go up to a 6", or is it better to keep the plant in a 5" even if it means repotting again in less than a year? Thanks!