I have the Chart View on my MX20. To me the jury is still out on the decision. The cost to add it to the MX20 is outrageous for what you get...a compact flash card with a little more memory than the one with the database that comes with the MX20 and a USB SanDisk loader. Basically about $100 worth of stuff. Then you have to call Jeppesen and buy their update subscription (you don't even get one with the money you give to Garmin for the ChartView). Every two weeks you get a JeppView CD in the mail. Download the data from the CD to your PC, run out to the plane to get the Compact Flash card, put the card in the SanDisk unit, download the data from your PC to the Compact Flash card and finally put the card back into the MX20. And if you can get all this to work the first time without calling Garmin's technical support line, you're a better man than I.
On the other hand I can't imagine any better situational awareness on an approach than having the actual plate on the MX20 moving map. You KNOW where you are. If the controller's gonna take you through the localizer you can see it coming. Another big plus is that it automatically puts the appropriate airport chart on the moving map whenever the groundspeed is less than about 50 kts. Very cool.
I've paid for the Jepp View for a year, so I'll continue to use it and form an opinion as to whether or not to spend another grand next year (in addition to the 430 updates and the XM Weather subscription, and of course the paper charts.)