russ996duke said:
Having bought a second hand sp3 for the occasional long/foreign trips I can get away with only snag is it came with mapsource 4 (I think) it would be nice although not essential to be able to update to V7...
Russ:
Let's set aside the whole matter of cost (and method of acquisition) and look at the storage and performance issues associated with running Version 7 cartography on a StreetPilot III.
As you know, the SP III is limited to 256 megs of map storage - and that's only possible if you happen to own a 256 meg chip. Chances are you have a 128 meg chip, because that is what most of the SP III's shipped with.
Since version 4 of the maps was released, the size of the map files has more than doubled - in fact, it has almost tripled. This means that you will only be able to fit half as big an area (as defined by population, which is the easiest thing to correlate map size with) at most on the same chip. More likely, you will see your map storage area - and thus your range of operation - shrink to about one third of what it is now.
In addition, since version 4, an enormous amount of Street Attributes have been added to the cartographic databases. This is good - it results in better quality autorouting - but the processor in your SP III isn't any faster than it was when version 4 was the current release. You will see a significant slowdown in route calculation speed (and screen redraw speed) if you switch from V4 to V7. Its very similar to upgrading your 486 computer from Windows 95 (which runs just fine on a 486) to Windows XP Pro. You can imagine how much the computer would slow down. The GPSR won't slow down quite as much as that, but it will slow down enough that you will notice it.
A good rule of thumb is to not upgrade more than twice on any given piece of hardware. In other words, if your hardware shipped with Version 4 (that is to say, Version 4 was current when it was designed), you can go to V5 without any problems, and to V6 with minimal problems. But beyond that, all bets are off.
If you do a bit of budget planning, it would look like this:
a) cartography upgrade cost - $150
b) bigger chip (256 meg) to maintain current travel range - I don't know for sure, but probably $150 as well.
Let's say, for sake of argument, that your current unit is worth about $250 used. If you sold that unit for $250, and added to that what you were going to spend on the map upgrade and what you would need to spend on the bigger chip - heck, you are darn close to the cost of a new 'small' GPSR, or a gently used fancy GPSR that is perhaps one generation old (e.g. a 26xx).
If I were you, I would continue to use the SP III with the version 4 maps, as long as it gets the job done for you. When you get to the point that you really want to have current maps, then buy a new (or used) GPSR that not only has current maps, but was designed to be used with current maps. Considering that you said "you only bought the GPSR for occasional long foreign trips", you might be better off spending $100 on a decent map pouch for the top of your tankbag, and paper maps for your destination. Keep the SP III on 5 mile range, so as to see the 'big picture' of where you are, and you will have the very best of both worlds for minimal cost.
Just food for thought.
Michael
