Yes - it means you'll have an extra level or two over people with equivalent SP. "Boohoo, I'm too high level." Is it really so horrible to wait for skills? Cuts the grind to have something other than the level to work towards.
Overhitting essentially costs you SP.
You are thinking in terms of getting an SP penalty from overhitting in that you get more XP but the overhit nuke makes the mob give less SP. Of course, it doesn't work like that.
What overhitting does is throw off the XP:SP ratio. Repeating trivial info for those who don't know: You get more XP, but your SP gain stays the same - unaffected by the overhit skill.
It seems that under normal circumstances, you get about 9-10% worth of SP when you compare it to the XP you get. When you overhit often, you degrade you SP gain alot. You lose SP as you level due to overhitting often. This is bad because NCSoft adjusted skill costs based on how much XP is needed per level. When you overhit alot, you get all the XP, but you don't get all the SP. That is why classes like Necromancer often can get all their skills at every skill level, even though they have more skills than most classes in the game - but classes that overhit often like Spellhowler and Spellsinger often have trouble getting all their skills and have to "skip the 'useless skills'" as a result.
When you overhit alot, you may think it's okay since you can just "skip the 'useless skills'" as you level, but when you get to S Grade it will come back to haunt you.
Half of level 76 wasn't enough for me to buy just Ice Vortex as 77 due to often overhitting mobs. I was over 2.1M SP short. Half of level 76 is alot of XP, but I basically went 15% faster becuase I overhit like 80% of the mobs (using both high level and D Grade Overhits) to level as fast as possible. Had I not overhit so much (like, had I been a Sorc), I would have probably had more SP than I needed.
How much SP do you think you'll be able to rack up for level 78+ skills seeing as how there is still a skill at 77 (the Fusion Seed) to get and there are like 3 level 78 skills. If you overhit that many mobs, that is.
Skill OE is in S Grade. Overhitting may level you fast, but once you get to S Grade you will essentially level slower than everyone else because they will have all the SP they need to OE their skills, and you will often not have enough because everytime you gain the necessary XP you will be too low on SP due to overhitting.
Skill OE costs uses the same formula that NCSoft uses for skill set cost per level.
The SP required is roughly 10% of the XP required. Actually, I think it's a clear cut 10%. Currently OE'ing skills at 0%, I always end up with .02-.05% left over after I go +1 a skill and that's becasue of the overhits :)
I guess if you eventually get there, you will see why people say they "lost XP from overhitting". ;)
Oh, and BTW, the amount of SP scrolls I had to buy to cover that 2.1M+ SP I needed for that skill (cause I was burnt out from levelin at that point) is not worth the extra speed in leveling.
With the way NCSoft balanced the Skill Set/OE costs in the game, you should not have to wait for much of anything if you don't "abuse" overhit skills (which normally come at a hefty MP cost anyways).