Maybe a little perspective from outside of Volcano will be helpful.
Clearomizers were a great choice 3 years ago, but since then vaping technology has gotten ALOT better. You might really like them, and while there's nothing wrong with that, the rest of the market has moved on to bigger and better things. The biggest issues with clearos is that they leak, they crack, and they don't wick fast enough for higher voltages. The products that have come out since the release of clearos have addressed all of these issues.
Carto tanks (ie the Tube Tank), replaceable bottom coils (like Volcano's new design), replaceable top coil (like the iClear30), and many of the rebuildable designs have clear tanks so that you can see the amount of juice you have left, as well as its clarity.
As far as your issues with Carto tanks. How long would you say it takes you to go through an entire tank? Did you fill the carto completely before putting it in the tank? I go through at least one tank a day, and I do not have issues with the juice getting gross until the carto is about a week old. It sounds to me like you are not completely filling the carto and it is burning the filler, which in turn will leach back into the tank. Or you are taking a very long time to finish a tank, which is causing the juice to naturally age in the tank. If you pour a little juice into a cup and let it sit out for a week, it will start looking gross by the end of the week because the oxygen in the air is attacking it, and causing the liquid to oxidize. Some people call this "tanning". It is the same reason that a brand new, unopened bottle of juice will be very clean and clear looking, but an older bottle that you opened a few months ago is darker. As juice is exposed to air, light, and heat, it will darken.
In regards to your issues with lack of resistance options, ohms really don't matter that much anymore. Now that we have the option of using variable voltage, or even better, variable wattage, you can adjust the device to compensate for any resistance you happen to dig out of the bottom of your (where ever you keep your old vaping stuff). Because a 3.0 ohm carto at 5 volts will preform almost exactly the same as a 1.5 ohm carto at 3.5 volts. Furthermore, if you press and hold the + and - buttons on the LavaTube 2.5, it will switch it to variable wattage mode. This will allow you to set your wattage to 8.3 watts (which is what a 3.0 at 5v is) and any carto, atty, etc you can find will vape the same no matter what resistance it is. You could be using a 1.5 ohm, and switch it out with a 5.0 and never notice a difference.
Expanding on this a bit, the reason Volcano recommends 3.0 cartos for the LavaTube is because the device is not able to provide more than 3 amps. Which is a round-about way of acknowledging that higher resistances are more electrically efficient. Your setup of a 3.0 at 5v is 1.6 amps. With a 1.5 ohm at 3.5 volts (same wattage), you are pulling about 2.4 amps. Fewer amps for the same result, which means that your battery will last longer between charges.
Another benefit to the carto tanks, is the cartos they use are dual coil. This spreads the heat out, which helps wicking, as well as keeping the coil temps down, which will in turn make the filler last longer before it eventually gets charred.
Going back to what you said about Volcano only selling 3.0 ohm atomizers. They also sell a 2.0 ohm (the Inferno Low Resistance Atomizer) and a 2.5 ohm (the Magma Atomizer). These work best on the batteries they are named after, but will also work just fine on a Lava Tube. But as I was saying earlier, since the LT is a variable device, you don't need to have a lower resistance atty. They also have 1.5 ohm cartos for the Tube Tank (marketed for the Inferno battery), but again, not really needed with the LT.
If you give tanks an honest chance, you'll find that they really are a better option. Volcano tends to be slower than the rest of the vaping market when it comes to new technology, but it's because they thoroughly test everything for months before they decide if they are going to sell it or not. So anything you see on their site has been proven to be the best of what the market had to offer when they released it. There are better options out there, and Volcano is indeed narrowing down the field to decide on what the Tube Tank replacement will be. But until then, the Tube Tank with a dual coil carto is the best option from them. I used to be a dripper, and even though I tried everything that came out, nothing could compete with dripping until I tried a DCC in a tank. And years later, carto tanks are still my mark to beat.
