So I retired my main party after going through the storyline as far as I can (except I did not defeat Veirna yet)
and decided to train up a new party or two after the Proficiency system revamp.

I discovered that having my tank pet attuned to Shadow was actually pretty useful as it had a chance to heal itself as it battled without worrying about its health going down so quick.
My battle pet is attuned to Water which is really great considering that "Frost" is granted pretty often which helps in battles; it may not exactly heal but definitely helps to slow down health deterioration.

Now..my magic user is attuned to Light only so it can heal the party bit-by-bit.
It is surprising because on my original party I had my tank attuned to Earth which was good but despite the high agility I tried to give it, it was still pretty vulnerable; even after attuning it to Shadow it did not do much but I suspect that pre-revamp pets may be at a disadvantage....maybe.

Anyways, what I like about the revamp is that you are not as restricted as to what pets can be what. A tank can still do quite well as a Shadow or Water because the adjusted equipment really helps fill in the gaps.

Also what is nice is that I can attune a pet and wait until it gains levels before using proficiency points because the stat boost is contingent on the pets current level. So I can wait until my shadow pet is level 26 before using a proficiency point because as the pets level increases so does the prospective stat increase.

In other words I do not need to waste a point right away bit rather just attune then wait for several levels to really reap the benefits.

At first I wasn't sure about the revamp but now I can see how well it works especially on the stat boosts so it seems to give a person greater leeway in developing a team that is not strictly confined as long as the equipment can augment areas that are lagging.