This is silly. If you have the liquidity, who cares if you have to wait 6 weeks for free money? This is why other exchanges are dry. Not everyone is a broke college kid for whom six weeks waiting for money is a life-stopping crash
MtGox withdrawal issues are huge. I wouldn't downplay their issues at all. Speaking from personal experience I had a $10,000 June/July withdrawal stuck for 8 weeks. Customer service wouldn't give any timeline.
After a lot of back and forth they said I could pay a 5% fee and get my USD in 7 days. Basically a bribe for them to convert to JPY and send the transfer through..
At the time, they said withdrawals would take 2 weeks.. Now if they say 6 weeks you should pray :p
I ended up buying back some BTC (at about 10% loss due to price) and then selling later on bitstamp due to the recent price rise. Worked out okay for me but please DO NOT USE GOX FOR USD.
Problem is, it isn't just 6 weeks. Not to mention restricting withdrawals is the same strategy you would take to prevent a run on the bank if you were insolvent. You should give it a try though and let us know how long it takes.
Anyone that quotes MtGox as the reference bitcoin price almost certainly has little experience trading bitcoin. Bitstamp is a much better reference price or if you want to be US centric CoinBase.
It's not that arbitrage opportunities don't exist in the Bitcoin world. There are some rare and fleeting ones. This just isn't a good one.