Firmly against a scrypt-N implementation. People saying "its GPU coin it should be asic immune" well there are none right now and you'll all soon change your tune when your R9 290's have to be RMA'd.
The R9 290 runs HOT no matter what. If you can't keep a reasonable temperature,
underclock it. I run Scrypt-N on my 280xs with no issues, and believe me or not,
EVERYONE says don't mine on a laptop. Well guess what, I have a 3 year old laptop
with a radeon 6770m and it hashes scrypt at 100mh/s for months at 73C. COMPLETELY
safe and within thermal limits. However, when I go to play my 3d fps games (which this
I7 laptop was made for), the GPU goes to about 85C along with the CPU at 90C. That is
about 5C too hot for me to feel comfortable, but after speaking with intel, AMD, and HP
about it, they ALL said it was normal and fine. That was 3 years ago, the laptop is still
going strong. I have mined Scrypt-N with it also. Mining will not kill my laptop, gaming
will since the GPU and CPU use the same heatsink/pipe, gaming uses both and the
thing really heats up, mining not so much.