Obviously we have significance in both the cases! Data compression save the stroge space and CPU time have much more significance towards running cost. In most installation's DASD cost per year is nothing compared to the CPU cost. For us 1 MIPS is $237 w.r.t. DASD cost of $5 per annum.
We should select between the two based on the frequency of the job and volume of data.
If the job doesn't run in daily basis and the volume is huge Compress would be the best option otherwise high CPU time everyday on yearly basis might bump up the YTD cost. Trade-off should be made based on the buisness requirement.
I have sent a mail to my Storage management team! But i am quite not sure if i will get a response before i contract ends ;)
So came up with another design were i commented the first step which compress the complete data. Used DATACLAS=COMPRESS only for delta copied from VSAM file. Used the 0th version to append to +1st version. Estimated savings is 50K per annum.