Unfortunately, I haven't had the pleasure of squeezing implanted boobs...many do look 'hard' [strangely, many of the D or DD cup variety]. But many implant jobs result in
soft and pliable boobs. Jordan is an example. In the current TV program here in the UK, she has squeezed her boobs many times and they are obviously and wonderfully squeezable.
And think back to favs Tiffany Towers, Letha Weapons, Sareena and Dusty, to name a few...once their implants were in for a while and the skin stretched, the result was incredibly 'natural' looking when they squeezed them.