It's actually even better, a potential 50% bonus to the healing output of Trance (compared to +5% on the Tiara, or about a 43% boost over the Tiara). That's the maximum potential, of course, assuming no time lost and no over-curing and so forth (rather unlikely, but theoretically possible!).
Here's the potential bonus to HP cured over time with the Salade for all Waltz tiers, under the assumption that you're riding your waltz timer and never over-curing, compared to head gear with equivalent CHR.
Curing Waltz +50%
Curing Waltz II +33%
Curing Waltz III +25%
Curing Waltz IV +13%
Divine Waltz +18%
So, under certain conditions, this stat can help you pump out more HP curing over time than the Tiara, but that's at the cost of increased TP expenditure, especially at the lower waltz tiers (which are also the least HP/TP-efficient). The Tiara provides a much smaller boost to HP curing, but it doesn't depend on timer-riding and it's also a boost to HP/TP efficiency.
The major question that came up for me was whether this large boost to the lower waltz tiers should alter curing strategy if there's a lot of HP to cure quickly and the Salade is equipped. For example, if you had the TP to burn, would it be faster to spam multiple Curing Waltz IIs rather than a couple of Curing Waltz IIIs?
However, for any practical value of VIT+CHR, the waltz tiers maintain their order in terms of potential HP/second. They even mostly maintain their order when compared between Salade and Tiara (i.e. Curing Waltz is slowest no matter what you're wearing, and Curing Waltz II is the next slowest regardless of headgear). Salade Curing Waltz IV comes up neck-and-neck with Tiara Curing Waltz III, and the Salade can push Curing Waltz III beyond Tiara Divine Waltz, but Tiara Curing Waltz III remains solidly ahead of Salade Curing Waltz II.
For example, here are the HP/second numbers for the Salade versus the Tiara, assuming 150 VIT+CHR, Casaque, Roundel, and non-Campaign Plectrum. (Roundel and Plectrum have only a very minor effect on the crossover points for the different waltzes, so the situation is the same with or without them, even when Plectrum activates in Campaign. But larger numbers are fun.)
Code:
150 VIT+CHR, Casaque, Roundel, 1% Plectrum
HP/second TP/second HP/TP
DW Salade 61.7 3.64 16.97
CW3 Salade 55.5 6.25 8.87
DW Tiara 54.5 3.08 17.70
CW4 Salade 46.4 4.33 10.71
CW3 Tiara 46.3 5.00 9.26
CW4 Tiara 42.7 3.82 11.17
CW2 Salade 39.6 5.83 6.79
CW2 Tiara 31.0 4.38 7.09
CW Salade 28.3 5.00 5.66
CW Tiara 19.7 3.33 5.90
DW numbers assume an average VIT+CHR of 150
So overall, for DNC main, the Salade with waltz delay down an interesting trade-off with the Tiara, definitely super-awesome for Trance, and certainly helpful for Healing Waltz.