First, DO NOT BUY THE HF WET TUMBLER IF YOU'RE CLEANING RIFLE CASES.
Now, keep reading.
Dry tumblers I've never used and never will. The media doesn't last forever, it's dirty, and unless you decap before tumbling the lead dust goes everywhere. Maybe it's cheaper than wet tumbler, maybe it's faster, maybe it's nicer that you don't have to wait for the brass to dry, but I don't think it's the best way to go.
Ultrasonic cleaners work best cleaning parts, but can work with brass, but it works best with large diameter cases like .45's. I have a Hornady and I only use it when I find a variety of empty calibers of all sorts laying around that isn't enough to do in wet tumblers. If I could go back in time I would have bought the Harbor Freight tumbler, it's more rectangular, fits longer parts and such and w/ coupon is quite a bit cheaper than the Hornady.
I prefer wet tumbling and I have both the dual drum you're looking at and recently picked up a FA Lite from Midway on sale.
You're probably wondering why do I have two wet tumblers? The reason is the Harbor Freight is not strong enough to do two full drums of brass, the motor used is the same as the single drum model and it causes the RPM's to drop enough to where cleaning isn't as effective as with a larger tumbler. There's also an issue of the HF using a belt drive and not a geared drive, so if you overload the HF and try to tighten the belt to get more power, the belt snaps.
I have some aftermarket belts that are MUCH better and can take the tightening, but if I tighten to much, the motor stops spinning because it's not strong enough.
I absolutely do not recommend the HF tumbler if you're doing rifle brass. There's not much space in the drums, you might get 100 pcs in each drum, but you'd be better served with a larger, REAL tumbler. If you're reloading pistol, the single drum HF tumbler is a good entry level wet tumbler. It's the cheapest option and for those who are unsure about loading, just getting into it, I don't blame them for not wanting to blow $150 on a larger tumbler only to discover they don't like reloading.
I do still use the dual drum HF tumbler for small cases or stuff I don't load much (.32 ACP, 7.62x25) and I like having the two drums because I can do different calibers in each drum and I do keep different size pins in each drum as I've found 9mm length pins will get stuck in the necks of .38, but not .32 and 6mm pins will get stuck in .32's, but not .38's.
EDIT: As for drying, after I rinse the cases under the faucet in the tub, I've started putting them in an old linen or cotton sheet or old undershirts, wrap the fabric so no cases fall out, and shake the thing around. The cases are drier and waterspots don't form anymore.
Not that waterspots mean anything, I just don't like the way they look.
You could also buy a cheap toaster oven or food dehydrator and put the cases in them on low heat for 20-30 minutes. You don't need much heat to dry the cases.