I test drove both the Tiara and the HQ Sweet 16 and was told by the HQ rep that they are indeed the same machine - the Tiara is made by HQ and re-badged for Babylock. Because the Tiara is going through an additional sales rep, it's quite possible that you can get the HQ Sweet 16 for a lower price - depending on your area - so be sure to check them both out.
I absolutely loved them both!! Within minutes I was micro stipling! I didn't like the stitch regulator, so suggest you try it first before spending the extra grand for that option. You can always add it on later.
I am definitely getting one of them someday ... I need to get my sewing room sorted out first.