Using technical words can be a good way to show technical people that you understand their business and their particular point of view and are on their side. That is, you do all of that if you use the technical words correctly.

The same is true of big words, in general. You don't hear these words often because they're so precise in meaning; and, worse, the only people who will understand what you're saying, the only people who will be impressed by your vocabulary, will also be the people who are most likely to know if you make a mistake using these words.

And it's easy to make a mistake with these words. You may be a bit vague on the meaning, or, worse, the word may have a different technical and colloquial meaning ("download" is one word like this in common usage today). If you employ the common usage in front of a technical audience, you merely highlight what you don't know. The downside of using a big word incorrectly is smaller -- you just confuse your audience (that doesn't make you look good, either).

So, if you need a technical vocabulary to impress people, then make sure to learn a few words very precisely. If you just want to look smart, then speak simply and clearly. Everyone will be impressed that you are able to communicate so well and with such economy.