I used to buy GW miniatures back in the day but always enjoyed more the actual boardgame. That's the reason my favourite GW game was Blood Bowl (I have 10 full teams, 6 and a half of them painted). I stopped buying Warhammer models because I found the rules clanky and moved fully to buying only boardgames.
I started buying minis again with X-Wing. At the beginning mainly for the collectible aspect, but I kept buying them because I find the mechanics awesome... I then tried Armada and Runewars and also find that FFG has kept a very high quality in their rules.
That's why I'm so excited also about Legion and the new bigger and better minis. I have all Descent 2 and IA materials and have been slowly painting the minis. The rules are great (as with most FFG games) but the minis qualities is average, so I think that, if by increasing the size of the minis they increase their quality, and maintain the same level of rules, it'll be a win situation for them and for us gamers.
I plan on using IA minis as proxys in my private games, but don't care much whether FFG allows them in official tournaments (I actually prefer they don't as it would detract from the aesthetics of the game)