i currently mine using vertminer.
here's my bat file (for r9 290)

setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
vertminer -o stratum+tcp://stratum-exe.poolz.net:3333 -u USERNAME -p PASSWORD --thread-concurrency 24450 --intensity 13 -g 2
pause

for a r9 270 you'll have to use a much lover thread concurrency, start around 75% of TC of standard scrypt
for example you can use --thread-concurrency 6336