The two are very similar in design, as other has attested to. The Filco uses a higher-quality PCB: FR-4, double-sided, and possibly thicker (I forgot to measure it). The Leopold I had apart recently used a low-end, single-sided FR-2 type PCB. It's been a while since i had my Rosewill apart, but I remember it being single-sided as well. The PCB quality isn't terribly important on plate-mounted keyboards, but it gives you an idea of where your money is going on the Filco (besides the brand).
All that said, the Rosewill is the best bang for your buck. I have a Rosewill, CM Storm and a Filco and they all have the same amount of heft and solidness to them. If you use a more flexible USB cable, you are less likely to have issues with the connector.