I think this is a great upgrade kit and have ordered 2 already, my S1's will have a new lease of life and my hash rate will go up, I just wish they would be available sooner.

I tend not to look at the ROI charts as mining is a very speculative venture and no one knows whet Bitcoins will be worth in the future. I am just content that I am supporting the network and that in the future I may see some rewards for this.

My initial investment in mining hardware for in FIAT currency, but all upgrades are in Bitcoin so I have effectively written off my initial FIAT investment and will keep churning Bitcoin for hardware until I build up a substantial reserve of bitcoins.

I will only know if this strategy is good in a few years time, but I am confident that eventually my investment will come good. Anyone looking for a fast buck from mining will be disappointed, today mining is a long term and speculative investment.

As an aside, it is also great fun to watch your miners racking up Bitcoins, certainly this is worth something in entertainment value alone.