I was at the optical store getting a new pair of glasses and lens. Since I have a somewhat high prescription, when selecting the features for the lenses I asked the clerk whether there is an option where the lenses can be made thinner than the regular lenses with the same prescription and she said yes, those are the high-index lenses and they cost a little bit more. Then I asked her since these lenses are thinner thus better, will it lose quality in other areas such as clarity, impact resistance, etc.. I feel the way I asked this is somewhat wordy and I wonder if there's an expression that means what I'm trying to say. An expression that describes the fact of getting something that improves its quality, but will in turn cause the lost of quality in something else sort of like a balance, I guess similar to the word sacrifice? But using sacrifice doesn't seem that correct in this context.
In my humble opinion, the word "trade-off" is most appropriate here. Sacrifice suggests loss, not gain. You would have to use both "sacrifice" and "gain" to obtain the meaning that "trade-off" provides in one package.
You could then ask:
"What are the trade-offs?" rather than "What do I sacrifice for these gains?"
This is similar to "negative externalities". These are basically things that are inherently included in any given action that are detrimental. Usually they are something that should not be ignored, but are at first.
For example, lets say everybody really wants a big Wal-mart to be built in their city, because it is cheaper and faster. At first the idea is great, however, a negative externality may be that people who own small businesses may be pushed out, and then they are worse-off than they were before.
I really love this word, it is the perfect thing to use in this type of situation. Also remember that there can be positive externalities as well! :)