Hi Neruz,
Yes, I've used Fantasy Grounds (but mostly Fantasy Grounds II for which you get a free upgrade if you have the original FG licences) for many great games with my regular group. We're in Australia, and cant always get to play face to face with our real world commitments. I've found it works great with 'fewer than normal' numbers of players ( 2 is great, three is about the max ) because the players get so much more into it and are much more likely to roleplay than sitting around the table. I think it tends to make shy players more confident and do and say things they would never do with their peers sitting right there. For example, I had one player rp his dwarf cleric/fighter with a scottish accent ( they always seem to have them ), and both players increased their CHARISMAS at 4th level because I was rewarding their excellent social interactions. I reckon we probably put away about 30 sessions at 2-4 hours per session, using downloaded maps and maps I'd mocked up myself using Dunjinni. FGII has a few great enhancements using the grid, tokens and token movement, and some cool stuff on the initiative tracker. If it werent for Guild Wars ( and steam in general ) we'd probably play a lot more! I do tend to think you need to instigate a few more rules before you can run an FG game properly. We tried to play using FG and a chat but we found the chat distracting and the players werent as confident, so we play just in text. I made a rule that the characters couldnt roll a die without my permission, otherwise they would just throw dice alll the time and you wouldnt know what it was for. We also use the different 'mood' settings ( that change the screen from light to dark, forest or fire settings ) to designate when the DM is or is not at the desk and whether the game is in progress or halted. I used PDF versions of modules and dragged them verbatim across into the FG storyboards and it works great!
We haven't tried 4th edition gaming in FG yet, but I understand some of the content is not open, unlike the 3.5 edition stuff. Going back and cleaning up some of the transcripts have made for some of the best reading ever! I couldnt say I was in a position to play regularly but I'm happy to jump in and test something out if you want to hook up.