the acrylic (wool) craft felt would be ok to use if you are not going to make something that will be washed...they do not hold up with washing...maybe gently rinsing by hand...but they are more for crafts that do not get laundered. marcus brothers puts out felted wool bundles that are only about 35% wool, they may be a better option. there are always alternatives...i have seen some beautiful penny rugs made with good quality double sided flannel, and homespuns. you do not have to use wool, some fleeces, and micro-fleece fabrics would make wonderful pennyrugs and they do not fray either...
good luck