I'd dispute the assertion that transaction times are slow, given that it probably takes at least 24 hours, usually more, for an interbank transfer to make its way through our decrepit clearinghouse system.

The 1MB block size limit is also something that can be changed in a future update to the protocol.

Outside of that, the 51% vulnerability is probably the most apparent weakness of the system.

In my opinion, it's unlikely that he alone is Satoshi Nakamoto, but not outside the realm of possibility. While he does seem to have the requisite understanding of the economics, mathematics, and (to a degree) the cryptography underlying virtual currencies, his previous work does not match the tone of the original paper.

The original paper contains concepts (Merkle Trees, Poisson distributions, Gambler's Ruin, Binomial Random Walk) that hasn't been mentioned in any of Szabo's past works. In addition, most of the references cited at the bottom of the paper seem to be outside the wheelhouse of someone with an Economics and Law degree.

My personal approach, if I had $10000 land in my lap, would be one of two options:

1. Wait until a more reputable ASIC vendor (read: KnCMiner, but up for debate) begins accepting preorders for their next generation of ASIC mining hardware, verify the stated hashrate will net you a positive ROI, and place your order as fast as possible. Usually, the farther from the front of the line you are, the less you'll profit.

2. Put your BTC into multiple exchange accounts, open a CryptoTrader Pro account, and let it manage the day-to-day trading for you.

Any ASIC hardware designed to mine Bitcoins can only mine altcoins that use the SHA-256 hashing scheme, since the underlying hardware is only designed to perform SHA-256 hashes.

As a result, it is not possible to use Bitcoin based ASIC hardware to mine scrypt based altcoins, such as Litecoins and Novacoins. (The scrypt hashing scheme has heavy requirements that ASIC hardware designed for Bitcoins probably doesn't meet anyways.)

Edit: You might want to take a look at the SHA-256 altcoins listed at http://altcoins.com/ if you're looking to mine an alternate cryptocurrency.