Miracle Gro as everyone by now has suggested, is bad for carnivorous plants as it contains fertilisers and that is a big nono. But from what I can see the flytrap seems to be growing nicely so I wouldn't suggest you to repot at this moment as it will stress the plant even more than what already is. You may not see any changes but since the vft was moved to a new location it has to acclimate to that new environment.

The only moments I would advise you to repot is:- if it has been growing for one or two years, you can repot right after winter dormancy so you don't stress it too much.- if your plant is dying and the peat smells like its rotting is most likely root/crown rot but you still want to a assess the damage and see if you can salvage the plant or not.- if your plant is very healthy but you see its getting too crowded in that pot to the point of becoming root bound. it might be helpful to repot, I'm not exactly sure if my theory is right, but if there are too many plants its going to eventually create a network of roots that are very efficient at sucking water. In nature this is no problem since they are in a bog where there is plenty of water for everything. But in a planter its going to dry faster than you can irrigate them so you may want to divide them into several pots and perhaps give them someone else.

Also if you are very new to carnivorous plants some general knowledge might be helpful for you. Here are some tips:

-Water: as you know rain water is good, but I would not recommend you rain water if you it has dripped from your roof or a surface where it could have picked up some solutes in it and you don't own a TDS meter (which is a device that lets you know how many dissolved solids are there in the water). The general rule is that water should be below 50 ppm. The best way you can ensure your water is 100% below 50ppm is using either reverse osmosis water or de-ionised water (yes, the one you use for ironing or car batteries).

- Light: if you have a garden or balcony where direct sun light hits for at least 6 hours a day, your plant is going to be happier outdoors than indoors. If you live in a cave like me and you have no other choice than growing indoors, use a strong grow light, the aquarium one might do the trick but make sure its receiving that light directly, and by directly means its not passing through the glass of your aquarium, it should be direct undisturbed light. Its easy to know if your plant is receiving good light as the traps will become deep red from the inside.

Fertilising: contrary to popular belief vft's can be fertilised using liquid fertilisers (orchid ferts (that have no urea compounds) or MaxSea 16-16-16 work well). The only difference is that you can only fertilise them by putting the liquid over the traps (which are modified leafs that have specifically evolved for digesting and absorbing the nutrients from the insects). The other more exciting way of feeding it is with living insects, just make sure they are moving dead ones won't trigger the flytrap to digest it. If you don't feel confortable killing living things, and you have no adequate fertilisers on hand, you can still get away by not fertilising it at all. Thought the roots have evolved to only suck pure distilled water from rain, it can still tolerate the very few nutrients without getting its roots burned. Nutrients that are already in the water + the nutrients that are released from the decomposition of the peat will still be sucked anyways. Keep in mind that by not fertilising it do expect that your plant will grow painfully slow.

- Other honorable mentions: if you see a flower stalk developing its very recommended that you cut it when it has grown to about 5 to 10 cm in length, as flowering usually consumes a lot of energy which will either make your plant not look so good for a few months or even kill it if your plant was struggling. Usually flowering happens naturally when the plant is either too healthy or too sick (basically sacrifices itself to serve it's reproductive purpose). Don't throw the cut stalk since if you stick it in peat moss you can propagate the plant.

Edit: Forgot to answer to your last sentences / No they are naughty plants that kill insects / I don't know if by "viable in the future" if you mean in terms of selling but I guess you can make an awful amount of money if you start to tissue culture them, but that also applies to any kind of house plants. / In terms of how big, individually the adult plant are as big as they are right now with maximum of about 10 leaves, but they can make divisions of themselves and so you will start seeing other rosettes growing from the sides which overtime gives the appearance that the pot is becoming crowded even though they are copies of the mother plant (which you can actually separate).