I have tried it twice and succeeded twice using upholdco's platform to convert my BTC to USD when I feel the price is falling, after it has fallen a lot and I see signs of it rising a bit, I convert my USD back to BTC. this worked good twice, but I wasn't willing to take the risk again cause it's again a gamble based on the price of the BTC, considering these days BTC price is pretty stable and would require a large amount to even benefit from small arbitrages.
What you are doing is not arbitrage, it's speculation-based trading. Arbitrage means exploiting differences in pricing at different marketplaces which occur at the same time. In contrast to speculation-based trading this technique is theoretically without risk. Practically however it is still risky if you can't execute both orders at the same time and the price on one exchange is changing to your disadvantage after you already have executed your first order.
I would not recommend trying Bitcoin arbitrage, because direct arbitrage is impossible due to transaction delays (both Bitcoin and fiat transfer). Even if you permanently keep fiat and Bitcoin at various exchanges to take advantage of arbitrage via distributed balancing of fiat/BTC holdings it's still difficult, because there tend to be systematic differences with some exchanges (BTC-e) being almost always cheaper than others (Bitstamp) in terms of BTC purchase price. In addition, Bitcoin generally tends to appreciate in fiat valuation, so it might be more lucrative to constantly buy Bitcoin than to try arbitrage if you use Bitcoin as your reference of value.
ya.ya.yo!
