Someone knows if there is a study correlating gaps number between this two chemistries?. Or in other words, there is less contigs using XL+ instead of XLR70?
It depends whether you are completely satisfied with the XL+ upgrade...Looking at the community and our own experience....the upgrade only gave lots of work, less data and excluding one run, short read data...
Since you are asking; are you experience something unusual when using the data? It migt be linked to this issue. See for instance seqanswers.com for more elaborate discussions on the buggy XL+ upgrade.