Long time between replies.... I did get back onto this, and solved my issue (Garmin Montana/Oregon).... I'll post it in case anyone else has had the same problem.
Trigs weren't displaying on the map well, whether found or not, presumably the term 'Benchmark' was not being interpreted by the device well.
So....
For found trigs, the following lines needed editing (do a find/replace all with a text editor):
<sym>Geocache</sym>
<type>Geocache|Benchmark</type>
<groundspeak:type>Benchmark</groundspeak:type>
and change Benchmark to a normal cache type, I chose Webcam Cache, as there won't be much confusion when GC caches are added alongside.
so these become:
<sym>Geocache</sym>
<type>Geocache|Webcam Cache</type>
<groundspeak:type>Webcam Cache</groundspeak:type>
(For found trigs (or other GA caches) - the line <sym>Geocache</sym> also needs to be changed to <sym>Geocache Found</sym>
Another touch is to add a custom icon for 'Webcam Cache'.... so now my trigs show up as little trigs.
This does involve some text file editing, but with find/replace, it only takes a minute or two.....
I also did a separate query for traditionals, changed their type as above to 'Mega-Event Cache' and then made a new icon, so I can tell apart GC/GA trads from a map glance now..... good fun....
The Garmin trig icon if anyone wants it.....
http://pics.ollie.eml.cc/pics/pics/Webcam%20Cache.bmp