Besides comfort, the other question is, and sorry to be crass about it .... are you rich?

If you use these miles for upgrade, you won't be able to use the same miles for basically a free round-trip flight in the US/Mexico/Canada, or a free one-way flight international later on.

If you can afford to not care about a free flight later and value 8-9 hours of sitting/sleeping in a bigger seat more than a free flight, then sure, go ahead and upgrade.