There's going to be a tradeoff between ease of care and the weight and space savings offered by down. Down is always going to weigh less and compress more when comparing similar temperature ratings. It's up to you whether you think that's worth the slightly more inconvenient care options (personally, I'm taking a down bag).
If you're okay with the idea of it, you could always spray the outside of your bag with permethrin. It's what I'm planning on doing, and should keep bedbugs from infesting it. If you do end up with bedbugs, it shouldn't hurt your bag to throw it in the dryer, which should kill the bedbugs (heat is actually what kills them, so washing wouldn't even do very much; if you think you'd have the time, leaving your bag out in the sun all day would accomplish something similar).
Sidenote: both of those things (just sticking your bag in the dryer or leaving it out in the sun) are pretty useful shortcuts to cleaning things that are hard to launder, like sleeping bags and pillows. The heat (and/or UV rays) will kill any bacteria and dry all of the moisture and oils in whatever you're wanting to clean.