i think this problem is based on the contraversal solution of adding the healing to the 'lisk.
in 1.1, basilisks were useful hunting down lone humans who were out for destroying outposts (or building them), or coming from unusual directions to the alien base. they were basically acting alone, especially since they are vulnerable to teamkill.
now healing drags them into offensive groups of bigger aliens, where of course the opposiotion is the strongest too. aka humans are coming in groups (not good for basi), aliens are attacking in groups (not good for basi, and for blocked teammates too), turrets are prolly nearby (not good for basi).
for attacking humans in groups dretch is much better as it blocks less, damages more and automatically, more agile, harder to hit, and less of a pain if it dies. the health of the basi doesnt compensate it at all.
so you can still act as a lone basi, without taking care of teammates but fill the 1.1 role, or you can sit in a corner and wait for the teammates to come for healing. with basi+ of course, since the s1 one's healing is pathetic, even for himself's few hp. if i'm hurt as a dretch but got a bunch of evos, i rather evolve to basi+ then to mara+ and lose that points, to be able to counterattack rapidly.
of course excellent basilisks are excellent, but mine is not. against a group of humans, from Saliva's list, i can only sacrifice myself on the altar of teammates.