The 997 (large, true to size recommendation) was a mistake for me. It does the job... however, it is at the cost of severe discomfort and inability to breathe for just enough oxygen to not feel a bit loopy after more than maybe 20 minutes. Though I notice much of the increased reduction comes from the flesh being smashed out to the overlarge armholes rather than the partial double layer on the front, honestly. Straps dig into my traps/shoulders excessively (very painfully, also affecting my neck), felt like my windpipe was even being depressed somehow. And the armholes pinch and dig in A LOT as well. And back pain, back pain, back pain... persisting for quite a time after a very brief wear of it. I don't even think if I were a really skinny/small-built guy that it would work for me either. And I'm really not that fat, I'm a mixture of overweight and above-average muscular right now but I also have a large frame to begin with, built exactly like my dad (normal male broad shoulder type too).
It's just absolutely not worth it (there's maybe 1-2" difference between a large 997 and a small 974 on me, really). I should have went with another 974 straight off, like I'd initially thought. I only wanted to try the 997 because I thought it might get me a little longer use before stretching as they're all wont to do eventually but yeah, no. Nobody can tell I have boobs in the 974 (and I am a D/DD) - even though this one I'm using is four years old now - (small is what works for me and WITHOUT any of the problems of the 997 in large; go figure), they all say they just look like pecs, that they wouldn't know if they didn't know etc. So I can live with that.
If I really need that extra little bit of compression at some point, then I'll take my old 974 and remove the cotton layer off of it and wear it with another one and probably still not have any of those deal-breaker issues of the 997. I think the problem is with the actual cut/shape of it than anything else... it's just not dialed in right. How cisguys can even stand to wear these ones is beyond me.
Anyway. Your mileage may vary, but 997's are a definite no-go for me. Will be returning for a refund and ordering the 974 (want to get two, just less confusing than exchanging and adding another on top etc lol).
Nothing against Underworks, but the 997 needs some serious improvement. I'd wager if they made the double-front into the same kind of sleevless-T cut as the 974, it would work and without a majority of those problems as the A-shirt kind of cut they for some reason made the 997 into.
Just my $0.02
Edit: actually, I think perhaps I'll give a 998 a go. Hear it is a sort of middle-ground option.