Are they worth the extra money?  They might be to you.  
I have the Hovabator 1588 and am OK with it.  It took a couple of hatches to get the temperature adjusted right, but that’s easier on the new model.  I keep it in a stable environment so don’t have trouble maintaining temperature.  It took a bit of practice but I got the humidity thing down too.  I strongly recommend the auto turner.  That makes life so much easier.
I normally only hatch twice a year.  If I hatched much more often, I’d probably upgrade.  It’s partly ease of hatching and partly ease of cleaning.  I get pretty good hatch rates but I have to pay attention. With the higher end models they do more thinking for you.  Adding water should be easier though if you have a hard water source, you might think about using distilled water so you don’t clog up the plumbing.  The Styrofoam isn’t that hard to clean with that tray under it catching most of the mess but I could see a problem if it got really messy, say if an egg exploded.  
I can’t say whether or not you will get better hatch rates with an upgrade.  Maybe, maybe not.  Some of the bells and whistles make them easier to use but realize I don’t use all the bells and whistles on my car, let alone all the cupholders.  
Are they more dependable?  Well, I haven’t had a problem with my Hovabator.