The bikes you are looking at are more entry level and I would not say a Rockhopper is any more or less trail or XC oriented than the Marlin. It sounds like you have settled on a medium, 17" frame, even though is sounds like you are not 100% sure. I would remind you that the standover height has much to do with the angle of the top tube, you will notice that frames which have better standover also have a steep top tube angle and usually have a gusset on the seat tube, for example look at the CS-041.
My suggestion is to look at a few more bikes at your LBS, figure out what fits you, and learn more about why you like the way the bike fits you. For me I look at the ETT, Stack, and Reach mostly for fit. Then I look at the HTA, chainstay length, and wheelbase to give me an idea of how the bike might ride.
Ordering a Chinese frame that you've never ridden can cause you to be hesitant. However, you can adjust the bars, stem, seat height, and seat rails which will adjust your Stack and Reach to give you a better fit. Compare that to the HTA, chainstay, and wheelbase, those are things that are not changing much.
I've gone from Trek and Specialized bikes to custom Chinese builds and back again. I like the ideal of building my own bike but I also like to demo bikes on local trails, not in a parking lot, to get a better feel for what I like in a bike. My tastes have really changed over the years, at first l liked a XC bike with a short wheelbase, and 70+ deg HTA. Now I'm liking more trail oriented bikes with short chainstays and slacker <70 deg HTA. The trails in my area are fairly rough compared to a lot of what I see people posting on this forum or on MTBR. So for me, it was more about smoothing out the ride, increasing grip, and getting a bike that felt like it had a lower CG. My previous bikes, a -057 and -037, were too XC-ish feeling. Once I demoed the Trek Stache, a light clicked on for me, the Stache was the type of bike I didn't even know I was looking for until I rode it. You may have noticed that Peter sells the CS-496 which is very similar to the Stache. If I were to build a hardtail today, that's where I'd be starting.
I'm no longer concerned much about weight, yes it's nice to have a 19 lb 29er hardtail, but what I think is even better is a 26 lb 29+ hardtail. I'm a bigger guy, 5'-11", 195 lbs, and for me I like the solid feel of a bike that digs in and grabs hold of the trial. Not a lightweight bike that bounces around a lot on the trail.
