Navigon have just released a free upgrade (patch?) for MN|6 available for download from their site. The upgrade has greatly improved usability and speed of route calculation and location of destination on the map. Prior to the upgrade I was a bit disappointed compared to MN|5 but wanted the additional east european maps that come with MN|6. Now it's at least as good as MN|5, plus all those extra maps
I've also experimented with installing MN|6.1 with various SD cards, i.e. PNY, SanDisk regular and SanDisk Ultra II. Surprisingly the fastest in terms of startup is installing onto the regular SanDisk card (and not into system memory). This is gives boot time of about 35-40 seconds compared with around 60 secs with the Ultra II and the PNY cards, and the same when installing into system memory. Strange that the high speed Ultra II is slower, but perhaps the high speed is optimised for writing files to it as in a camera, and not for input/output operations when running a programme like MN|6?