If the camera shoots AVCHD at 17mbps, the AVCHD-DVD disc will look the same as one burnt to BD media.  If the camera shoots HDV-MPEG2 at 25mbps, the output to AVCHD-DVD will still be AVC at 17mbps or less.  It may, or may not, look as sweet as if one burns to BD-MPEG at 25mbps.  An owner of a camera that shoots 1440x1080i HDV-MPEG2 would have to furnish an opinion.  A connoiseur pixel-peeper might make a fuss, but the lay viewer would not notice and balk mainly over whether the content was boring, the dubbed music was a favorite, or the camera was too shakey. 

Unless I'm mistaken, the AVCHD-DVD format does not allow for bitrates higher than that.  So if you have a camera that shoots 24mbps, then there may be some IQ loss if you compress.  A way to "trick" Pinnacle and burn discs at higher bitrates is to select the BD-MPEG disc image option.  But, when burning to disc, you insert an ordinary blank DVD disc and use the "burn from previously created image" in the AVCHD-DVD creation setting.  However, the amount of video you can put on a single DVD-SL will be less than if you use the AVCHD-DVD approach throughout.

Otherwise, the main advantage of Blu-ray over AVCHD-DVD is the fact that BD allows for much longer video and at potentially higher bitrates than 17mbps. Some users of PS 14 also reported a pixelation problem in clips longer than 8 minutes, when creating AVC output (AVCHD-DVD or BD-AVC), which they could avoid by burning to BD-MPEG.  I don't know if PS 15 fixed that or not.