Technically yes, but the difference is that VMware actually writes _everything_ into that one file vs wine proposing to write just what is written to the boot sector into a file..
The reason it is different, is because it is much more difficult (if not impossible) to tell what is boot sector and what isnt if you have a file that contains an entire drive's worth of data.
Anyone techinicaly adept could find the MBR, it's the 1st sector on the disk, this isn't about boot records but the MBR which is in a known place. I recon you could use linux tools on your windows hard drive to retrieve it easy.