I have just purchased a drive on the basis of your comments, and following testing with a plug-in power monitor you will be glad to hear that your figure is about right:
Plugged in but switched off: 1W (6VA)
Switched on, no drives installed: 5W (10VA)
Running with 2 drives, idle: 17W (27VA)
The drives were Seagate Barracuda 7200.10 250GB - not particularly energy-efficient, but fairly typical mainstream SATA drives. Interestingly the power consumption dropped over the first few minutes after switch-on with the drives installed to the figures I give above.
The power overhead of the enclosure is pretty good, all things considered, so you would certainly be entitled to mention this in the marketing material. For comparison, an Iomega Ultramax two drive enclosure with similar drives fitted consumes 26W (47VA) when idle - 50% more power. The DAS200 is much quieter in operation as well.
The only minor negative comment I would make regarding the product is that there is no upper rail to help locate the drives when installed, as is the case with some other similar products. This means that unless you take the cover off and secure the drives with screws (reducing the ease of changing drives if necessary), the drives are not as well located as they could be. Since hot-plugging is supported, this is a slight issue; but certainly not a big deal.
In terms of support for Macintosh systems the enclosed CD-ROM does not have a version of the SteelVine Manager software which is compatible with the current version of MacOS X, which is 10.5.6. A version which does work OK for uploading firmware etc can be downloaded from the Silicon Image website. However I can't imagine how the email alert function offered by this program can work for a drive of this type - I imagine it is there because of other NAS-type products using the same chipset but this is presumably not deactivated on systems which don't have any network connection. Not a criticism as such, more an observation.
With all of its features and its very reasonable price I would have thought this product would have been very attractive for the Macintosh market. Have you considered getting it reviewed by MacWorld, MacUser and MacFormat, etc?
I hope this is of value to you.
Regards,
Nick