Looking at getting some new wheels for my 29’er hardtail – have spotted some cheapo lightweight chinese jobs that I think I’m going to take the risk on.
BUT, they’ve only got a 19mm internal width.

I’ll be using these wheels solely for xc races, thinking of sticking a Bontrager 29-0 (1.9) on the front, and Maxxis Aspen (2.1) on the rear.
Generally running 20-30psi and would weigh ~68kg kitted up.

Will it be grand, or will they be burping/rolling on me in every corner?

I have run 19mm rims on my 26″ hardtail for years, and given I am both a larger chap and tend to ride in the Lakes/Highlands/North Wales etc on rocks and stuff – and have had few problems, you should be fine!

I run tubeless if that has any impact.

That said, I did uprate my 29er to something a bit wider as I thought the 19mm rims it came with may be a bit narrow, especially with tubes and my old frequency of pinchflatting when I ran the 26er with tubes many years ago!