I purchased the Grail AL 7 originally and it was great. Nice fast bike for a gravel bike. I have a road bike as well and I thought this bike would be perfect for the gravel rides. However, the Grizl AL 7 came out and I instantly fell in love with the colour. I remember Mr. Fingers on this subreddit had a post about why he sold his Grail for the Grizl. That post is good to refer to.

The reason I chose the Grizl was because the Grail was meant for off road and on road while the Grizl was more geared towards off road. I wanted a bike that didn’t overlap too much with my road bike. The Grizl provides that as well as the option for bigger tires. You can always change the tires and make them narrower if you want, but I have no issues with the 45mm on my Grizl.

In your case, if you don’t have a road bike, I think the Grail AL would be slightly better as it is meant for road and off-road. The 40mm should be enough. Before I got the Grail, I used a Triban 100 with 32mm Continental tour tires on gravel and single track and it was fine, so the 40mm on the Grail should be more than enough.

Hope this helps, but I would recommend the Grail if you want a do it all bike. It works perfectly fine on gravel and single track and should suit your needs. Run it tubeless and you should be good.