You don't think Firefox is a worthy competitor at the moment? I've used it quite happily in the last few years, but would be interested in what you think its shortcomings are. I know there is supposed to be a power drain issue, but I haven't noticed that personally. Apart from that, I'm not aware of any major issues.
There's an 8 year old issue in Bugzilla for this.[1] The Firefox team has finally put some resources into fixing it, but progress has been slow. I'm not holding out much hope -- Chrome has had this feature for a long time and it's never worked quite as well as Safari's.
A Firefox multi-touch zoom extension also exists[2], but it's not smooth enough to be useful to me (admittedly, this is on my old and slow 12" Macbook).
