Resist-based sets are not the best for Scrappers, especially if you don't intend to trick out their defense. Since Scrapper resistance caps at 75%, they're mathematically unable to achieve the same level of performance as a Tanker or Brute with the same powerset.
It's not that it wouldn't work; an /Elec Armor Scrapper would certainly be viable. It's just that if you're going for resistance instead of defense, you'll get more mileage out of a Brute. Scrappers tend to shine in defense-based sets, where they can match survivability with Brutes and come out ahead in damage.
De minimis non curat Lex Luthor.
Basically, the Scrapper resist cap means you get less benefit from /Elec's very high energy resistance, and from Power Surge. Also, the scrapper version of the damage aura does not have a taunt component, so enemies are more likely to run from it. These definitely do not cripple the set, but scrapper vs brute is mostly a toss-up anyway, so /Elec having a few points in the brute's favor tends to tip the decision.
Edit: On the plus side, scrappers get Energize eight levels sooner.
Yes, you get less resistance than a brute, but you will get more damage from the scrapper primary. You want more damage with the combo? Go Scrapper. You want more resistance with the combo? Go Brute.
Edit: TW might get better damage on a brute, so if you want tw/elec, I would go brute.
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Brutes getting Fury to boost Lightning Field where as LF doesnt crit, also puts ELA in a Brutes favor.
With Staff/ELA being the pairing mentioned, Brutes would get the better resists. Solo wise, Energy Resist for sure, and the other resists if you take and use the Tier 9 godmode.
Brutes as mentioned will also make out more from Fury helping build up LF's damage.
However, I think Scrappers (think being the key word here) will do more damage with Staff Fighting though, due to Scrappers generally making out more from +DMG buffs. But the Fury built LF will help even that out.
while I prefere Scrappers myself, I admit my FM/ELA wished for LF to have a taunt aura, as lots of enemies ran from LF and FSC. 
It wasn't to the point of so annoying I quit. More like, "Ya know, sometimes I just wish..."
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My main is a KM/Ela Scrapper and he is a beast. However the lack of a taunt aura in LF is VERY frustrating. AVs will run from it, which will make you want to beat your head on a wall.
There have been several times I had considered re-rolling him as a Brute, but I had already started badge collecting, and everyone said KM sucked on brutes compared to scrappers.
One thing I would like to bring up though is Power Sink. At lvl 50 it will bottom out all but an AV's end bar, and LF can keep it there. That adds a lot more to survivability than it is given credit for. With the right combo of Incarnate powers I have bottomed out the end of GMs and kept it there.
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So, I don't see many posts about it. Does it just completely suck or what?
I have a fun concept for a Staff/Electric Char. Sort of a Lightning Rod-type guy.
Anyone out there with strong opinions on it Pro or Con? Is it end-heavy? Squishy? Badass?
I'll probably try one on the Beta server, but I know I won't level him fast enough to get a real taste for it at mid- and high-levels. So, thanks for advice.
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