All three heatsinks I have mounted in longitudinal direction, since the only coarser openings are available in my case. (Here bought a set with the Pi)
I have before and after once hired by a point gauge comparisons. (However, at room temperature in the summer) I could find no significant difference, but that's always difficult. My rudimentary measuring tools I do not ascribe to the waterblock.
Do I really want to express a buy recommendation .... I'm not sure, since I'm not yet convinced of the cooling effect of 100%. Anyone who wants to soothe his conscience and (believe it or not) 1.47 incl. Shipping has, may well strike without hesitation.