Yeah, 170+ slides is quite a lot, especially if they contain images as well as the usual text and graphics.
I've never used Keynote, as I've always worked in a company that uses Microsoft Office as a standard. I'm presuming Keynote can export to a Powerpoint format? If so, are there typically any imperfections in the exported file when viewed in Powerpoint? I don't do any funky transitions, or anything complex - just straightforward text, colored boxes/lines, and a few images pasted in.