I have successfully converted all my '17s to FT except one. As my collection grows I am starting some breeder colonies of mice and rats (actually tomorrow) but for now and the next couple months FT is all I have as well although I have access to live. Every one that I got from breeders were being fed live and all took FT on the first try with one exception. The key seems to be the temperature of the prey. I generally thaw at room temperature in my snakeroom which seems to elicit feeding activity. Then I heat the thawed prey with a hair dryer until the entire rat-mouse is over 100 degrees and the head is about 110 measured with a heat gun. My Pastel Vanilla girl is being stubborn. She even hit and wrapped on two occasions but left it and never ate it. I am picking up a live rat pup tomorrow to try that.
Most will switch over once 200+g without much issue but there is an occasional stubborn one like my Pastel Vanilla. She will get it but as my breeder rodents start to produce I am probably going to switch to live prey I produce for cost and ease of feeding. Once my breeder collection reaches 20-30+ FT will be a huge pain and every breeder I know feeds live prey with no issues at all. I was a HUGE holdout on only wanting snakes that are established on FT but its not always possible when searching for specific genetics.