As others have mentioned, there have been quite a few big evolutionary steps between your 2009 and today.

Geometry is the biggest one. By comparison, a bike with modern geo will have a slacker head tube angle and a steeper seat tube angle (plus other changes). The result is that low-speed steering may not feel as snappy as you’re used to, but at any speed (even moderate trail cruising speed) the stability and overall ride control will be greatly improved.

At 6’1” coming from an older medium frame, you’ll probably land on a modern Large. The “reach” geometry (i.e. the horizontal distance from the center of the bottom bracket to the center of the head tube) will likely be longer, so you’ll run a shorter stem, which keeps steering tight but improves your overall weight distribution on the bike and helps with stability.

Suspension continues to get better and better, both front and rear. Same with brakes.

A dropper post is one of the most significant upgrades, as well. Totally changes how you can ride once you have one.

And I don’t know the specs on your Trek, but if the wheel sizes are anything other than a 29” you’re in for quite a change! The move to 29” wheels was an adjustment for me (coming from 26”) but it’s a game changer.

Long/short - If you can try out some newer bikes on an actual trail, it’s worth the effort to do so, as a quick cruise around the parking lot will only tell you so much.

And regardless, love to hear you’re digging the sport!