I'm hosted with JSWeb (after MUCH frustration with 3 other web hosts), and I can't even begin to express how impressed I am with their servers & service.
I just held a grand opening for a new site which focuses on product downloads that average between 20-40mb a piece. On day one, I got 85 new customers who all downloaded several files that day. The site didn't drop. No really, that - to me - was absolutely amazing. Honestly I was so happy, I felt like crying!
My site is blazing fast. They offer you the option to have them install a fresh version of Zen for you, which I opted for, and I HIGHLY recommend this (you can import your database, of course). They know their servers, and their install is tailored for them, along with a handful of extremely useful (not gimmicky) mods that enhance performance and interfacing esthetic. For the record, I've mod'ed my shopping cart like crazy, and also maintain 2 other popular opensource apps on the same account, with no problems.
And get this - I've got one of their pretty basic packages. I run a home based business with a modest budget, and I had always saught out "affordable" web hosting "solutions" ... it always turned out bad. Now I'm paying just a little bit more than I was before, for a PRICELESS, honest solution.
I usually don't do things like this, but then again - It's rare that I'm so impressed with a company or product. Thank you JSWeb!