Balance of virtual gestalt?

[Belial_the_Leveler]

How balanced is the following system?

1) Class/LA limitations as per gestalt.
2) Advancement is not actual gestalt; after you decide on the sides, add levels of the two sides together in a single progression, with abilities, feats, BAB, saves and skills according to the full progression.
3) Treasure is twice the side level instead of the full level.
4) Epic Feats become available at side level 11, except for Epic Spellcasting which doesn't exist.
5) ECL of the party is 4/5 the full level, rounded up.

For example, at virtual gestalt 10, you could build a Fighter 10/Wizard 10 as a 20th level character but with twice the treasure of a 10th level character. You couldn't build a Fighter 15/Wizard 5 though (or the reverse) as max level per side is capped at 10. You couldn't build an Eldritch Knight either as dual-progression PrCs are not allowed in gestalt.

[Beardbarian]

This is just so wrong

[aleucard]

It took me a while to wrap my brain around what you're proposing. In short, this would be even worse than normal. At the end of the day, you're still only marginally better than a normal character at the areas that really matter, and most combinations don't even get that much. For instance, the best way to use Wizard spells generally don't need attack rolls of any kind, so the +5 BAB doesn't really do anything useful, and the only thing that REALLY helps survivability at standard-op is the Good Fort saves. Being this far behind on the most important metrics just simply does not do you any favors.

For a counter-proposal, how about this? On level-up, the player may choose to gestalt rather than do an actual level-up, starting from level 1, taking a permanent LA +1 for the trade. This sets them back by half the XP required to level up to the next for each level gestalted. If 5 or more levels are gestalted (may vary depending on the combination), the LA increases by 1. The player keeps track of what each roll of their HP dice gives them; at each individual level gestalted, the player rolls their potential new HD, and takes the better of the two. If the new class has higher Skill points than their original one, they receive points as if they started the character as gestalt. Prestige classes may be selected for gestalt, but the character must have been able to qualify for the PrC at the level he slots it in (IE: if putting in something with a prereq of +5 BAB on a level 10 character, the earliest they can slot it in is at level 6).

EDIT: To frame my proposal in a more helpful way, what you really need to do is ask exactly how powerful gestalt is. To do this, you need to answer 2 big questions. Is a player allowed to take caster levels on levels of PrC's that don't advance casting, and do these additional ways of modifying the character's abilities account for the difference between this and the next spell level? While answering no to the first won't necessarily restrict Gestalt's power all that much (there's several perfectly fine PrC's that don't lose casting, after all), it's just that little bit extra. In general, though, unless if you're doing something to the tune of RKV//Clericzilla, gestalt MIGHT be able to account for a full spell level of difference, but it'll be much closer than you'd think. Two or more is not a contest. While people around here like saying that versatility is power in 3.5/PF, really there's just no substitute for actual power, and spell levels are how one gets that in these systems, with the exclusive exception of things like Shadowcraft Mage or Incantatrix, but I don't need to go over the difference between those monstrosities and most other PrC's, now do I?