I'll give you every single ZL1 owner's response in advance: yes, absolutely, it's 1567815 times better, there's no comparison etc.
For more nuance, let's consider what you already have and what the delta gives you. The 2SS 1LE has all the comforts, bells and whistles, with the same 1LE advantages you have been enjoying. If you care for these things, but not that much about the extra power, it is probably a better choice (meaning less of an immediate cost).
If, however, you are after "moar powah" and/or want to be in on the top dog owners' game, compounded with the rarity of a last model year car, go for the ZL1, it's undeniably the best Camaro trim. Unless you go to a track or are willing to take serious risks, though, you won't be using the extra 200 hp that much. I know, I should probably shut up with my extra 400 hp over stock, but driving the car at 2/10ths most of the time and occasionally at 6-7/10ths may not be everyone's cup of tea, so to speak
