Not sure where to start, but you seem to be looking at the right things.
Compression is "standard". Ref
https://h20195.www2.hpe.com/V2/GetPDF.a ... 358enw.pdf https://blog.purestorage.com/pure-stora ... reduction/ http://recoverymonkey.org/2018/05/23/ne ... -and-nvme/ 3PAR uses LZ4, Pure uses LZ0 and Nimble use LZ4 on older arrays and LZ4 + something else for newest models. So if you have 3.5:1 on an older Nimble you should expect the same on a 3PAR. Not sure how Nimble produces the 3.5:1 figure though .. Could be that they count zero blocks into those numbers to inflate them as many others in the industry does, but most likely they are inflating dedupe in stead.
LZ4 provides the best performance all over, but provides a slightly lower compression ratio over LZ0. LZ0 provides generally the same compression speed as LZ4 but decompression is slower.
LZ4 is genrally chosen for use cases where performance is key.
Now, from a birds eye view, the 8450 and 9450 seems to be rather similar... But if you take a deeper look at the quickspec you will see that a 9450 has 2x ASICs and 2x CPUs per node, while the 8450 only has one. 2.3333x the cache isn't bad thing either....
As for real numbers to share you are very vague... You have 7200c and 8200, what do you consider a large 9450? 2TB RAW (256*7.68TB SSD) capacity or 200TB (48*3,84TB SSD)