Obviously, we all have different thresholds/tolerance/preference for chemicals, bugs, etc.
I am kind of surprised that you are so careful about the avoidance of chemicals on the one hand, and yet, seemingly nonchalant about the avoidance of bacteria/viruses on the other.
You mention the First need as "huge, expensive, and heavy". I suppose that's necessary since it has to be mechanically good enough to take care of even the tiniest of viruses. But still, it compares quite favorably with many popular filters -- such as the MSR Miniworks.
Maybe you already know this, but just in case... the better mechanical filters have a filter size of 0.2 micron -- good enough to filter out cysts and the larger bacteria -- but NOT good enough for viruses. Per Denis below, the Timberline filter pore size is 1.0 micron -- or five time bigger. The Seychelle filter size is 2.0 micron or ten times bigger! This is why I paired the Seychelle with chemicals -- in my case, the chlorine dioxide would kill the viruses and bacteria first, then the Seychelle would block the larger stuff (cysts, protozoa) and remove the chemical taste.
Again, each to his own, but for me anyway, I find it odd that you would go way out of your way to avoid chlorine and yet you don't seem to mind viruses. I've read that viruses are rare in the wilds of North America... but if you follow trails, esp. the popular ones, then viruses are potentially there... Anyway, just my two cents.