Look for Frank Caggiano's response re: Aperture vs. Lightroom. He mentions -- convincingly 😉 -- that the problems you read about are entirely blown out of proportion. I have many hundreds of thousands of Images under management in Aperture. It works great.
It is a hardware glutton, but that is pretty well known, and shared with Lightroom.
As for the choice of one or the other: they are functionally similar enough to be considered identical (including having the same number of problems). Aperture has two main advantages: it's organization tools add a significant extra dimension, and it is much better integrated with other OS X programs (not a surprise). LR has one significant advantage: much more widely installed, and (thus) much more information readily available.
I suggest using the one you like to look at. I am serious.
Best of luck. There is no reason at all to be "nervous about taking the plunge" -- the learning curve for each progam is easily walked, after you swim across the "but I thought Images = files" moat.