This is my first DSO... I've also got a cheap 50Mhz chinese made (Dick Smith branded) analog scope.
I considered the 100Mhz Rigol, and I also considered the Owon SDS7102 discussed here:
https://www.eevblog.com/forum/index.php?topic=4412.0.
I decided against the Rigol as it seemed to be lacking memory depth available elsewhere, and decided against the Owon because of the number of complaints about firmware bugs. I've learnt the hard way that you can't rely on any vendor to fix software bugs. Once they've got your money, most of them don't care.
The Owon was very attractive, especially with its much higher resolution display. The Rigol is the benchmark in low cost entry level DSOs. The Instek seemed to be reasonably good value, a recognised and respected brand, and with more memory than the Rigol seemed like a good choice.
The one thing I would love to see on my Instek scope is a higher resolution display like the Owon. I probably would have paid another $100 for this.
I probably would buy the same scope again. the menu bar down the side is ok, but it would be nice to have some more screen real-estate available for the trace.
Bear in mind, I'm far from an expert on DSOs, and probably could have done more research before buying. There may be something offering better features, a better display etc for the same or not much more money, but ultimately I'm happy with my purchase.
If you buy locally like I did, bargain them down with online pricing. The starting price on this scope locally was nearly $1k. I pointed out that their price was double the online price delivered, and they came to the party with a good discount.
I'll check tonight and see if there is a way to get rid of the menu as your sales guy suggested, and check the firmware version for you too.
Cheers!
-Shaun