I think this is very accurate. My one criticism of Hana's slice BH is that she guided it too much, particularly when she was nervous. When she knifed through the ball it was extremely low and penetrating. But sometimes, especially against Evert, she floated the ball too much so that even if she got depth it didn't penetrate and pin her opponent into a predictable pass. Steffi, as we all know, did not have that problem as the knifing, almost vicious, slicing motion on her BH made it a formiddable, sometimes controlling shot.
Otherwise, Hana had a flashier and more dangerous backhand that could win baseline rallies as well as be an effective passing shot.
My biggest criticism of Steffi's BH id her lack of body flexibility. Too often her crosscourt passes veered towards the middle of the court with little angle. If she had enough power on it to handcuff the net rusher it could work out by eliciting a short mid court response allowing Steffi to close in with a forehand. If not, Steffi was put on the defensive.
On the volleys, there's no contest between the two. Hana understood the angles of the forecourt better and had more of a sense to win the point. Steffi, too often, tried to end points on one volley when two was required. She did not cover the net particularly well. The funny thing about the two is Hana's strength at net was her low volleys and half volleys. The hardest shots to make, she made them to look easy. Where she was sometimes shaky was on high volleys and, as BTurner pointed out, the overhead. Too much time to think and too easy to choke. Because of this, watching Hana play doubles with Kohde was nerve racking. Both were shaky on high volleys.
Steffi's absolute strength at net was crushing high volleys and overheads. Don't lob volley her unless you mean it because you might eat a fuzz sandwich. On the other hand, you want to feed her low balls, again, especially to the BH side because of rigidness and sometimes lack of ability to turn properly to that side.
The serve definitely goes to Steffi. Hana's first serve was effective when confident, but nonexistent when not. More than any other player, Steffi made Hana pay for bad serving. That was her #1 problem in playing Steffi in that she coukdn't her serve enough against Steffi. And since Steffi was so difficult to break, if you can't hold your serve then you have no shot.