So, we all know that summons could mean a big difference in the D:OS battlefield, there's nothing small about another meatshield (definitely on the cc-front) that also could do damage and do other nifty things. It was pretty clear the game was balanced around a party of 4, and if you summoned in 4 allies the game couldn't quite handle the amount of opposition.

So instead of balancing summons or summoners around this, limiting summons (as most 'balancing' progressions tend to do, just look at Baldur's Gate I and II) I would propose a full 180.
All characters have a summon/pet. All the time. Even without skills or abilities.

This way you can already from the start offer more intricate combat (8 vs AI) and don't have to balance for both 4 contollable characters till 8, but always 8. Such 'pets' could even have item slots and with certain powers and skills you can mold them however you want, always taking in mind they will be less customisable or powerful than the 4 "heroes". A party of 4 with their pets as shields? Possible. Ranged pets to help do some damage while playing defensive? Possible.

It would come close to old games that allowed you many characters (like Baldur's Gate) but at the same time slightly lessen the complexity by making part of it simpeler. Also it's a sollution to the much heard complaint already of loot. It would open entirely different loot-drops so even if you keep the same drop-rate, diversity is improved and the D:OS "swamp" as talked about in some other threads is already in itself tamed even without making any changes in that field.

You might wonder. Why would you be Master Summoner if everyone has a pet? Well, aside from improving your own you could boost the entire team. Instead of making a summoner just about calling a more powerful summon ("height balance") you can also take an entire different route ("depth balance") and instead buff all the summons of your team. And boy, can full pet-wide buffs change the field. Or would you rather have that one powerful beast? Choices, choices! And we all know that's great in RPG's, not?

LASTLY,
Another suggestion I already made for D:OS but didn't made it, and maybe now I no longer propose it near the beta, but rather before too much is done it might even make it in. Since I definitely think it would enhance the game, while it would take work to make it visually appealing.

The suggestion? Do not bind power to skin. WHAT? This means you can pick any "pet/summon" you want and the power isn't directly bound to them. You don't have to sacrifice your fluffy favorite wolf for an uninteresting and dull lesser elemental just because it's more powerful, the extra power is not directly related to the skin chosen.

However that doesn't mean that the path chosen cannot affect your pet. For example taking the wolf, going on a poison route could add sickly veins and distinct green burning on his teeth. Going for fire makes him look rougher instead, with a fire in his eyes. A summoner boosts him to be more powerful? He grows in size. You unlock a summoner team boost? Tufts of fur will fly off floating to your other pets, etc. etc.
Obviously as can be seen it would be more work than simply "summon other animal, more powerful!" but I personally think the added effort would pay off in the game. Especially if Summoner is chosen as one of the Skills and more emphasis on this area is put anyway.

What do you think?