Yea, you could. If you're running Windows you have builtin backdoors from the get go. It doesn't have to be all or nothing though. Plug the leaks that are easy, and try to work on the rest later. If I have two programs to choose from, and they're roughly equal in features, I'll take the libre program every time. There's no real reason not to.
Open source code is a feature, and that'll make up for deficiencies in other areas. The value will vary per individual, but it does have value. If Libre program's interface isn't quite as good as Proprietary's, but otherwise has the same features, the fact that the code is open can push it's value above Proprietary. Open code is a huge value, but it's harder to weigh against features that can be benchmarked. The individual has to set the value, but that value should always be greater than zero.
With open code, you get security from the masses. You may not be able to read code, but there's a good chance that many people who can have reviewed the code, and deemed it safe. It's an ongoing security check on the software you run. A dev can insert malicious features, but since the review is continuous, it'll most likely be found out. The software can then be forked, and the malicious features removed. Most devs won't do that though. Since money isn't the primary objective, their reputation is worth a lot more. Most wouldn't risk their reputation over something like bundled adware/spyware.