I've used them before, you'll need to go nuts on them for a very noticable aroma. Be careful with the bittering hops, high aa% means you can make it much more bitter than you intended to...
As Rob said you do need a load and to add them late.
I did an APA with a mixture of 6 malts and boiled for 90mins adding the Amarillo AA 10.7% at, 15mins 57g 30IBU, 5mins 85g 18IBU and 1min 28g 1IBU, it came out lovely :thumb: