I had had the soft shaker but needed more projection so bought a medium pair as well. These do project more but sound a bit harsher, which is more apparent at slow tempos, so I usually join them with the soft ones to even that out with some extra texture. Rather than twisting 2 halves together though, I like to join 2 pairs - one above the other - with 2 rubber bands. The rubber bands (a wider type) fit perfectly in the gap between the black centre and the coloured parts.
The shape and material of the shaker also allows for crashing a cymbal occasionally (that's something I wouldn't do with a metal shaker or an egg shaker that's too small for the purpose).