The Sony Reader will let you read PDFs that aren't DRMd. (So do most other ebook readers.) If you can open them on your computer with Acrobat Reader, not Adobe Digital Editions, they're not DRM'd.
However--they'll be shown in a 6" diagonal screen. Which means roughly 3.5" x 4.5" of viewing space. A lot of technical books suffer at that size. There are two ways of dealing with pages too small to be usefully readable: Reflow & enlarge the text, and zoom into sections. Some ebook readers do one; some do the other; some, I believe, do both. Neither is optimal.
Reflow changes the formatting, sometimes drastically; how badly depends a lot on the program that was used to make the PDF. Zoom, of course, is a hassle to deal with, and fairly slow on e-ink screens.
Right now, there just isn't a good way to read letter/A4-sized PDFs on a portable reader. This is not a flaw in the readers, but a problem with PDFs, which are page-based formats. PDFs that are designed for small readers look great; PDFs designed at paperback size look okay. PDFs that are scans of paper books are the worst; they don't resize at all.
A small netbook or ultrathin laptop might be more useful to you. You might check the "
See a device near you" thread to see if anyone near you has a reader you can test with real files before you make a decision.