Wyeast 3278 Lambic Blend vs. 3763 Roselare

Last summer I brewed two beers, one with Lambic Blend, the other with Roselare, about three weeks apart. They're now about 7 months old and tonight was the first sampling. The Roselare was INCREDIBLE while the Lambic Blend was just so so, with depressingly little sourness for that long in the carboy.

My beers weren't identical so this is not exactly an apples to apples comparison. However, I'm curious if others have noticed that Lambic Blend (3278) takes longer to achieve sourness than does Roselare (3763).

I've heard Lambic is not too impressive the first time out, but gets better on the second pitch on the cake. I used it for the first time a few months ago, but did pitch some of my house bugs with it, so I should be fine.

Did the beer have high IBUs (> 10)? The alpha acids in hops inhibit the souring bacteria, so if you used too many hops, you may not get much souring. %abv also inhibits the souring bacteria. They are supposedly inhibited in beers with more than 8% abv.