Hi .. we can't speak for the Platinum, but we can speak for the Meridian Colour, having owned and used one for the past four months. It's a fantastic geocaching tool.
The battery life isn't any different from GPSrs that we've previously owned/used (ie: for marine use, geocaching use or otherwise). The tinted screen sometimes makes it a little difficult to read in certain lights (less than 10% of the time), but we very quickly learn't that re-pressing the 'Enter' button, brings the screen back into 'readable' light!
We have only once lost satellite coverage with it, and that was in amongst dense manferns (it only lasted for 30 seconds max). Very different to our previous GPSrs!!
Having said all that, we are still aiming for a Navman Pin.
Would you like to make an offer on our Meridian Colour? ..
we didn't ask your advise????.... Now to the subject.. I own a Magellan Meridan Gold sence september 2004 and it has done me well for what i wanted an now im into this geocaching it has a new use for me 
..I just haven't figgered out how the WAAS is supose to work an that is all as i got my first cache today??? 
Number 2 WELL i forgot that i got a Magellan Meridian gold pack for under $1.000 come with a 64mb card , mounting bracket , 12 volt adapter , discover aus cd roman a bonus aquapac to hold your phone in while im in the water paddeling to the Island for the cape barron find 
