Blyxa was a no-go in all of my no-tech, low light planted vases, but I've got one remnant going strong in my 37g low-tech/medium light setup. Might be coincidence on the timing, but it was melting with no growth in the tank while in the mixed fluorite/gravel section, but rebounded and started putting out healthy green leaves and significant root growth when I moved it over to a newly added sand section (tank has sections of sand on the far right/left with fluorite/gravel along the back and filling the middle section).
Stargrass grows well in my no-tech planted vases in the higher ranges of low-light --but shows a very rangy growth pattern with thin leaves and long stem sections between leaf nodes. A very different plant than under high light/c02 conditions. Still useful--but very different.