The basic idea is sound, but as @scpickle said it won’t work with three-way switches because that’s just not how they work.
3Way Switches
For example, the GE switches which use the physical traveler wires have a zwave master but the second switch is not Z wave and wouldn’t actually be seen by either smart things or wink. It only communicates with the master over the physical traveler wires. It doesn’t talk to the hub.
IFTTT
IFTTT is very popular, but the lag time varies from account to account. At my house it’s a pretty consistent eight seconds, which works fine for many use cases, and we rely on it heavily. But there are other people who have a lag time which is either much more variable or much longer.
We should note that different triggers have different lag times as well in some cases. One of the fastest is sending a text so if it happens that you use case would allow for, say, smartthings to send a text to your IFTTT number and then have that trigger a wink robot then that might be pretty quick. IFTTT is a totally free service (it’s paid for by the manufacturers of the devices) so it’s worth trying to see if it works for you. See the IFTTT discussion in section 5 in the following
IFTTT is going to be the most straightforward method, it’s just a question of whether it’s fast enough for your particular requirements.
Philips Hue Bridge
Another option which would work more like your original idea is to use the Phillips hue bridge as a man in the middle. The Hue bridge can allow for many different connections, and I believe it’s possible to have it connected to both smartthings and wink. (If not, it’s a Wink limitation and you would have to ask them.)
If you have a V2 hub, the most recent hub update now polls the hue bridge every 5 seconds instead of every five minutes. That means if wink turns a Hugh bulb on, SmartThings will know about it five seconds later. So communication that direction should work pretty well.
I don’t know how long it takes before wink knows that a Hue bulb has been turned on or off, though.
zwave secondary controllers
If you have rooted your wink hub there are a few other options but they require a lot of technical experience and chances are if you had done that you would’ve asked your question in a different way. So I’ll just mention that some people have connected their two networks but The set up is pretty complicated and the outcome isn’t perfect so it’s not going to be the first choice for most people.
My recommendation would be to start with IFTTT and see if that works. It gives you two way communication, you don’t need to use any additional devices, it’s easy to set up, and it’s free. The only question is whether it’s fast enough.