I have. I actually have assemblies from a bumper and flipper here exactly for those reasons.
This is what I've learned:
1. Pinball coils need more voltage than we like to deal with. The coils I have are from very early EM machines,they do function well enough at 12v to work, so providing you match coil with power supply you should be ok.
2. Real coils are quite loud. Likely louder than the contactors. This could be a good or bad thing depending on where your machine will live.
3. The contactors are a complete little package. Easy to work with where flipper assemblies and such are just that, assemblies.
4. Sourcing second hand coils isn't that much easier than contactors and the price can be high. New flipper assemblies are relatively expensive too. Cheapest I've seen is about $35.
5. Flipper assemblies use a special dual voltage coil where dual coils are charged simultaneously on the initial flip, at it's highest point a second leaf switch engages that disconnects one of the coils, halving the voltage across the total coil which is enough to hold the flipper up, but prevents burn out. This slightly complicates the wiring, but also adds complexity and a mechanical point of failure in the assembly itself. It's not difficult to work with, but something to keep in mind.
6. Current draw on the real coils is likely above the ledwiz limitations meaning you need a relay of some sort. Don't quote me on that as I haven't measured it. It's just an assumption.
So overall the contactors are just simpler, provided you can get them. Bolt them in, connect some wires and away you go. No reason why a similar real coil assembly can't be as easy though, if a cheap, pre-made, available part can be found it would be every bit as simple. With the correct coil it can work with 12v, certainly with 24. So if you know someone that wrecked a machine and doesn't want the playfield that can be a good way of scoring the assemblies. Remembering that we only want them for the feedback it doesn't matter if they are worn and don't work well as real flippers etc. They'll still be good enough for sound/feedback.
The coils make sense in respect that you can mix and match. I might end up using a mixture of contactors and real coils so that all the feedback doesn't sound the same. Bumpers should sound different to flippers and slings for instance. I am also considering making an arc of wood across the top of the machine with 5 coils/contactors on it from left to right so I can be a bit more specific about where on the table a certain effect happens. Though I may not too as all current configs use 8 and if I use more than that I'll have to redo the configs to suit.
Get some of each and see how you go! You'll always be able to sell the contactors if you don't use them