I've been to the Ardennes on quite a few occasions with my road bike and absolutely love it down there. The thing I don't love so much are the climbs and there are lots of them of course. If you do the Amstel route there are also cobbles which can destroy a bike if it's not set up properly. So I'm currently researching the sh!t out of gravel e-bikes which means I can get a boost on the climbs and leave the power alone for the rest of the time without worrying about riding a big heavy bruiser of an e-bike.
I also go to the Veluwe a lot and currently use an MTB for the gravel trails but I'd prefer a gravel bike tbh so it would prove its' worth around there too perhaps.
At the moment I'm finding there are pros and cons, especially when it comes to the limited range of drive systems and batteries and groupsets. Price is also a big factor and you're not doubling the price of a decent non-electric gravel bike. You're quadrupling! So it's a major investment just to get a slightly more enjoyable riding experience.
If I can wangle the purchase tax back claiming I can use it for my (Dutch) business (delivering stuff to clients etc) then I'll plump for one these beauties:
3T Exploro RACEMAX BOOST