Would you build an item with +/- stats?

I think an interesting design space would be items that offer increased stats compared to other counterparts, in exchange for negative stat modifiers.

For example, a gives you +40 AD for 1300 gold. Would you buy a different item that was also 1300 gold, but gave you +50 AD and -15 armor?

That's the simplest example. Essentially, the idea is that these items would have more positive stats than their gold value, but with negative stats to balance it out.

These sorts of items would open up interesting design space and create opportunities to really customize a champion. If you are winning trades, you could opt for the lower armor in exchange for extra AD to push your advantage, or there might be a mage item that offers tons of AP and mana, but at the expense of health or magic resist. Skilled players who understand their matchups would know when to take the "safe" item that gives them a fair amount of the stat they're after, and when to take the risky buy that offers more power.