terminator

Definitely not good. If your running 3.7V @ .25ohms that's a draw of 14.7 amps. The battery would try to provide the current an be stressed way past max limit. The results could be really nasty. That's only 54 Watts.


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Good battery
Yeah you could buy a 3rd and add it to your mix. 

Yeah.  I just looked it up
 
You want high drain IMR batteries only to be safe
 
That battery unprotected and only rated at 4amps.  Maybe not catastrophic in a regulated device but not worth the risk at all!!

@Tam  As usual you speak like Athena...the goddess of wisdom
Terminator needs to go to a B&M and handle/play with the mods to see what will meet his needs best.

Edna gives good advice. What one person loves may not work the way another person wants. Vaping is so very subjective that it's impossible to tell someone else what to get and *know* it'll work well for them. We can tell you our opinions on what we use and know, but it'll be up to you to make the final decision on what to buy and hope it works out.   

I've had mine since May and I use it the most out of all my mods and it's NEVER let me down ever.
I don't have the pico mega it's the first one they came out with and I love it. I don't use the melo III tank much though I prefer my Toptanks and Avocado. I guess the question would be...If I did break it would I race out to buy another... the answer would be.....YES without hesitation .
 

I use a toptank mini on a pico as my everyday vape and I'm very happy with the set-up. I use both pre-made stock coils and the rba and it's not hard to build on once you practice a little. One thing though is sometimes you'll get a bad coil and that's a pain. I found that after trying a lot of different tanks and rba's the toptank and an avocado are my go to's and they're reliable work horses.

If you are looking at tanks to use on the Pico, then aesthetically the Toptank mini is going to look better.  The Pico is 23mm wide.  The TFV4 is 24.5mm in diameter, so there will be overhang.  The Toptank mini is 22mm in diameter.  They are really very different tanks.  However, if aesthetics don't really matter to you, then some of the things to consider are:
The TFV4 is a larger tank, both in physical dimensions and in capacity.  The standard single coil RBA deck that comes with it is larger than the Toptank mini RBA deck.   I don't have a Toptank mini, but I do have a couple of Subtank minis and personally I hate building on those RBA decks.
I find the TFV4's method for filling to be more convenient.  The top simply swings on a hinge.  On the Toptank mini the entire top needs to be unscrewed and removed.  
On the flip side, the TFV4 is prone to leaking whereas I have rarely experienced a leak issue with my Kanger tanks that wasn't caused by atmospheric conditions, such as extremely warm weather.
Replacement coils for the Subtank mini are cheaper, but the TFV4 has many more coil options.  The TFV4 coils also seem to last longer, so depending on your vaping style, you would likely find yourself changing coils less frequently.  If that's the case, then the higher cost combined with the longevity is basically a trade-off.
Most (but not all) of the TFV4 coils are really meant for sub-ohm vaping.  They do have a couple of 1.5 ohm coil options, though.  
The TFV4 is really geared toward DTL (direct to lung) vapers where the Toptank mini can be used for MTL (mouth to lung) vaping.
So again, it really comes down to what your preferences and what you think will fit your personal vaping style the best.  If you are dead set on one of those two tanks, then I would recommend making a trip to a B&M that carries both tanks to see if they have one of each you can physically compare side-by-side.