They can aid in recoil absorbtion/balance, provide protection, etc.
...
Are they worth it..? That is only known by those that have them..
I'm sure, just like the 1911's, they add/aid ones back-on target performance, as they do help spread out the recoil via absorbing more than one without one.
Does the 220 need one, no, IMHO, as my P220R DA/SA has performed flawlessly, especially in one handed or weak handed "reliability" without missing a beat, now, thru just over 1800 rounds..
As mentioned, hammer placement when cocked is much higher on a P220 than a 1911's. And, with "some differences", one being all 1911's are SAO, and are, for the most part, carried locked and cocked and having the beaver tail also serves, besides recoil aided balance, as, possible, hammer bite protection which the P220 needs none and like a SAO 220, also being carried locked and cocked, I suppose the beaver tail could aid one in protecting the hammer (getting hit) by anything, anyway, being dropped, etc., and qualifies the beaver tail, IMHO, as working benefit in many ways vs no beaver tail on a P220, so is it needed..? That is what each must weigh, cost, benefits, ccw (less chance of garment getting hung-up on one - without one) vs one with a beaver tail, what type of shooting is the gun going to be used for, SD/HD, ccw, competition, etc., is the question.
Those "with them" will swear by them, and well they should, as will those without them, like me, that would swear by them as well..
"Little things/changes, can, make big differences for most..
But, either way, they are fine, dependable, accurate, shooters.. either way with or without
No one will argue their merits on "the things that count"
OMMV,
Ls