The Latitude didn't have all of the limitations that the Sov+ initially had. Many of those Sov+ limitations have been removed with the latest Garmin software. Garmin seems to move much quicker with improvements compared to the other avionics OEMs... YMMV. Despite the same engines, and fuel capacity of the Sov+, the Latitude isn't as fast, or have the range of the Sov+ due its larger cabin...which is also what affects the few hundred feet in field performance difference. The issue with the Sov+ is to have its speed and range you'll pay $2M more than the Latitude, whereas the Latitude has the much better cabin. Other than the larger tube they are 85% the same airplane.
There have been a few SB/SLs that have come out for the Latitude but they are little things that are product improvements in areas that are different from the Sov+. The only issue in my airplane was an APU ECU failure. No problems since its replacement. I know of a couple of Latitudes that have had Entry Door lock pins retract too far, and cause the handles to jam. Growing pains of a new design.
Updating the G5000 is really pretty easy once you get the hang of it and understand what to look for in the process. I struggled a little at first using Cessna's cheat sheet. Now that I know what it's doing in the process it's a breeze. There is a bit of power cycling that takes place, but I updated the Nav and Obstacles DB's today in less than 10 mins of sitting in the airplane.
Having a lot of PL21 experience, there are things that Collins does better than Garmin. But...the G5000 in the Latitude is a nice presentation, very intuitive, user friendly, and pretty easy to adapt to. I have a few gripes, but most are pretty negligible. The SVS is good, and the AP/ATs are smooth and precise. Although, I have better luck with the ATs off during a very windy approach.
To 733driver's question, the Latitude and the Legacy 450 are competitors in mission profile. But in design, they are far apart as old school/new school. With the Latitude, it's a proven, and reliable design. With the Legacy 450, time will tell.