Here's how I see internals in the end - There are two types of internals: Stat boosts and generic abilities.
For stat boosts, the only way I can see them working is if their boosts are a percentage increase tied to an existing stat. Example: Advanced Armor Fusor - You reconstruct 20% of your maximum armor over 20 seconds. In contrast to internals with a flat increase: Advanced Repair Kit - You gain 40% more health from life orbs. Flat increases obviously benefit certain classes more than others, leading to inflexible builds. Tying internals to a class' preexisting strengths and weaknesses should mitigate this problem. Examples:
Deflectors - Reduces damage taken while boosting by 1% of your max armor.
Reconstructor - After being out of combat for 10 seconds, your mech regenerates 2% of its max armor every one second.
Repair Kit - (Note: Life orb repair rate is now based on a percentage of your max armor. Let's say 5% every one second.) Life orbs now heal 8% of your max armor every one second.
However, stat boosts can only completely work if every class has the same generic offense/defense/movement tuning options. I doubt a class without a booster tuning option or a strong default boosting stat will ever take a booster improving internal.
For generic abilities, I notice some internals and items are basically partial implementations of class abilities. I think those internals will improve if they work like abilities instead of being active all the time. Examples:
Armor Fusor - For 10 seconds, taking damage causes the armor fusor to build repair charges. When the effect ends, armor fusor repairs 15% of damage taken in the last 10 seconds over 3 seconds.
Fuel Converter - For 5 seconds, taking damage instantly fills 1% of your fuel tank.
Power Surger - Your run speed increases by 10% for 12 seconds.
As long as generic abilities don't mean damage or recovery without a downside, they shouldn't be an issue.
Finally, I think its possible for almost every internal to have 3 different slot sizes. The differences simply need to be proportional. Two slots should have double the effect of one slot, and three slots should have triple the effect of one slot. To prevent superior choices, downsides for larger slots come in. However, they're only downsides to the point where each slot version balances with each other. Examples:
Armor Fusor - For 10 seconds, taking damage causes the armor fusor to build repair charges. When the effect ends, armor fusor repairs 15%/30%/45% of damage taken in the last 10 seconds over 3/6/9 seconds.
Power Surger - Your run speed increases by 10%/20%/30% for 12/8/4 seconds.
Deflectors - Reduces damage while boosting by 1%/2%/3% of your max armor.
What the downside actually is depends on the mechanics involved. If the effect is minor, then simply giving up a slot is downside enough. Other downsides could be taking damage, a delayed effect, or a combination of downsides.
Edited by HugeGuts, December 29 2013 - 09:32 AM.