My take on heavy duty sewing machines is that they’re rarely needed. I sewed my jeans kilt on my friend’s ordinary 1980’s era Singer home machine. It had a little difficulty and I swore at it a few times, but all in all it completed a very demanding job just fine. My Bernina is not a “heavy duty” machine but it would do the same job without breaking a sweat - we sewed even heavier gear with it and it just plowed right through.
One of the things to look out for is that so-called “heavy duty” machines are usually less precise than ordinary machines, making stitches that are less even, and often fouling the finer threads on the bobbin hook or casing due to looser manufacturing tolerances. This, in my opinion, is worse than a machine that’s slightly underpowered (use an appropriate, new, sharp needle and help the feed out gently and you can work your way through it just fine in nearly all cases). When I tried to use the Sailrites to do nicer things they were extremely awkward and balky and the results looked very homebrew. With a modest quality home machine (I’m not talking the cheap plastic ones, but a well made vintage or a mid-market modern unit) you shouldn’t have any trouble doing anything from midweight leather to jeans to canvas to sailcloth. If all you’ll be doing is heavy canvas, and you’ll be doing a lot of it, ok, maybe getting a more specialized machine makes sense. But for cases, bags, covers, jackets, patches, all the way to t-shirts and slacks, you’ll be much better served with a more standard well made tailoring machine.
Edit: Also, Sailrites are just rebranded Chinese knockoff machines. You can find the same exact machine much cheaper on various eBay sites. And my biggest gripe with them is that the reverse and the stitch length lever are one and the same and it’s difficult to reverse precisely when using short stitch lengths - it needs an awkward hand gesture with lots of force. They make it look easy in their videos and yes, you can get to that point when using large stitches and sailcloth that’s well taped, but for slippery fabrics where you need two hands to hold everything in place, and stuff you need to make with more grace and precision, they just aren’t the right choice. A sewing machine with reverse on the pedal is AMAZING for the finer quality productions and details like straps/webbing, pockets, etc.