Hello there , I just ran in to this forum and thought would register just to make this comment since I moved to Mac 3 years ago , and still trying to settle for an InfoSel equivalent !! I loved Infosel and still do, I have been using it since 1999 and used MemoryMate in the mid and late eighties , (still have the original 5 1/4 inch disks of MM!)
I proselytized every chance I got about it . When I headed a major IT dept in 2004 ,  with 50 satellite offices , I wrote to Info Sel to come to an arrangement to develop a version with RTL support so it is usable for Arabic. They told me that it would cost me $120,000 plus buying a licence for each user !!!!!! This was really a great disappointment, even a major international IT consultant laughed at their proposal : pay all the development cost and not even get a reasonable number of free user licences. I have kept checking any new release of InfoSel , as they apparently worked in a two years upgraded interval as far as I can tell , but this upgrade is delayed I guess since they were waiting to get  a new version with Windows 7 . A great software but poor customer and business relations ! So thats my InfoSel experience. As far as the Mac the best close contender is DevonThinkPro Office and Eagle filer . But they are not all in one as InfoSel is , but then you can't compare a Windows to Os X .