I do not know much about the technical specifications of gravel bikes for racing or competition. My only experience is the Canyon Grizl: ON used for purely recreational purposes on road surfaces, bad pavement with lots of cracks, severely eroded asphalt that is like 'gravel' in that there is a lot of pebbly broken road with lots of sand, segments of easy to moderate singletrack, and even short, very easy rock gardens. Here's what a typical section of road looks like-- and the photo tends to minimize how deep these potholes and cracks are. They are nasty:
For this terrain, it's probably the best solution all around. There is one trail in my neighborhood that I have not tried-- I *might* try it on the gravel bike if I first assessed it on the eMTB and the conditions were not too extreme. But one key factor: My feet, and the bottom of the bike, is much closer to the ground than on either the eMTB or the enduro-style Marin TSDZ2B build, which was between an enduro eMTB and a gravel bike. I do have light 'toe strikes' on the Grizl if I am careless and pedal through maximum lean when cornering. Therefore, I would worry about one or two drops on my 'moderate' singletrack route in the neighborhood-- again, the one local trail I haven't tried yet.
That said, there is one ridiculous spot in one of my routes where the pavement dips briefly and abruptly from about 12% to 20%, and I seem to have plenty of clearance for it. I actually walked the bike over it first to make sure it could make it, and had no problem. It's no harder or more dangerous on the gravel bike than on the eMTB or enduro.
The pleasant surprise is how much easier the flared drop bars are on my hands given the bad osteoarthritis in my metacarpals and carpals, the base of my thumbs and everything connected to it. I am almost always on the drops, though more recently, I've been moving to the tops of the bars during climbs. (I have to remind myself to do this, it doesn't come naturally.) It is less upright than either the eMTB (obviously) or the enduro (which had back-swept bars), though I do notice my triceps get a much better workout on the GRIZL, which is fine. No back strain that I have noticed.
I am glad Stompandgo mentioned the suspension, there are now a handful of electric gravel bikes with suspension (the BMC URS amp LT Two,
Specialized Turbo Creo, the Canyon Grizl ON, Topstone Neo Carbon lefty). For the 90% of the terrain I ride, I fine the Grizl no less capable or less comfortable than the eMTB except: There can be rare segments of moderately bumpy road that just happen to be at the wrong spacing / resonant frequency for the frame and suspension (40mm, much less than either of the other bikes) at speed. There are just one or two spots like this on Mt. Hollywood Drive and Vista Valle, no longer than 50 or 100 feet, and they are hard to see when you are hauling ass. (Note the photo and the long shadows that can hide potholes!) That's the only place where I feel that less travel in the front suspension, and seatpost suspension as opposed to rear suspension, hurts performance just a bit, though I think it's mostly having less suspension in front, and something about the carbon frame, which theoretically provides some suspension of its own in the vast majority of situations-- just not this one. It's just different; maybe riding technique will eventually overcome this.
That said, in many situations, the Grizl has better traction than the enduro-- for example, applying hard pedaling and lots of power at the end of a sharp corner on bad road. For whatever reason, the back end does not break away as quickly as it did on the Marin enduro. I don't know why; the tires are much thinner, and despite what lots of folks say about the TSDZ2B, the Bosch SX feels like it delivers more power and has more grunt.
I haven't owned the Grizl a year yet, but even on good pavement, I've noticed that on descents, the speed where I start to really feel like the bike would be hard to control avoiding a dog or encountering unexpected / hidden bad road seems to be about 38 MPH. I've had the eMTB up to 43 MPH, but that was on slightly better road. Some of this may be getting used to the handling, particularly having the confidence to not grip the bars quite so tightly.
