Hmm...
Well personally I stick to cartos because of the convenience. Frankly I think I'd be close to quitting or going back to cloves if I had to deal with carts and attys again. I just hated the mess of filling them up and the inconsistent draws; gurbly and fluidy one minute, dry a few later. Just not my personal cup of tea.
That however isn't what you asked.
I can say this: I have a 902 atty. I just plugged it into my sidesho batt and pressed the little ole button and yep, it glows. So yes, a 902 atty would work with a sidesho batt. Advantages? Not many I could think of beyond 2. One it is larger and holds more fluid. Two you could get a Low Resistance atty. If you're unfamiliar these have lower resistance so they burn hotter. I believe they approximately mimic smoking at 5v-ish , on a regular 3.7v sidesho/902 battery. Also a passthrough does much the same; delivers 5v instead of 3.7. Combined they were TOO much for me. I like warm flavorful vapor, not burnt steam.
I would expect the 902 atty would work on a 510 battery since the threading is identical but I couldn't guarantee that 100%. I will say this though: My roommate has a tornado (ego) battery and he uses the same 510 cartos that I use on my sidesho and 902 passthrough so... if 510 cartos work on a 902 passthrough and a tornado and a sidesho battery, yes. They're all mostly interchangable.
I've smoked his tornado. It puts out 3.1v (It has a circuit to limit it down to that which helps extend battery life and lowers the chances of blowing out an atty). It put out (this is with a carto mind you) roughly the same vapor as my 902 5v pass through, just slightly less warm. The main advantage is the battery life; especially with the new slightly longer batteries they have that have 1000 (or maybe a bit over) mah.
To me that's the only real advantage to a tornado/ego; the battery life. Not a bad advantage mind you but I haven't noticed any better taste or the like.
Frankly I think a bit too much is made of "more or less flavor" from the equipment. If you spend 5$ or 500$ on a battery or battery mod there are only 2 things that can change: Battery life, and voltage. 3.7v or 3.1v or 5v or 6v will "taste" exactly the same being pushed through the same atty or carto no matter what brand name device is pushing that current.
That's why my two main focuses are battery life (which I take the 902/sidesho pcc into account for because frankly it's not large to carry and I don't consider swapping out a battery every few hours an excessive burden), and customer service. Voltage is voltage is voltage.
And as for delayed replies.. we're a smaller group on this forum so it can take a bit
**I went back in to edit "gurbly" to "gurgly" but decided I liked it as is. Kinda combining "bubbly" with the onomatopoeia of "gurgly". Be damned, I'm sticking with it!