3 minutes rest between each; it was done in supershoes. First felt very easy, second felt pretty easy, and the third was more difficult but not that hard. It was more mentally difficult than physically tough, and my HR only went to 95% of max on the last one.
I've mainly been doing long tempos (8-10 around 5:20) and similar volume of shorter reps in the low 5:0x range. What's a reasonable goal for XC?