I think he's capable, but it's really hard to evaluate lawyers. The cases are unique (as to defendant, evidence, details of the crime, jury, and so on), and you don't get to replay trials with a diff atty and see who did better or worse for the client.
His reputation seems to be solid.
It's also hard to dig out the full story on cases after the fact. But here's a bit of info on a few, the parts I can find.
1 Murder of Sarah Walker 2007 - Went to trial and Gore got his client the death penalty. Collin County. Three-and-a-half hours of deliberation.
2 Attempted-murder-for-hire case in 2009 - a hired hitman who didn't carry out the plot, and told the intended victim. He was charged, but charges were dropped before it went to trial, and he probably testified in exchange.
3 Murder-for-hire and search issue - (NOTE: This is the situation you noted, but you apparently didn't get all the facts) (Rough outline of the case only) In 2008-10, there was an issue over Judge Rusch (the same judge in EA case) authorizing a search warrant for physical evidence in Gore's law office against his client M L Bell in a murder-for-hire case. The evidence was found. The warrant and details about it were contested, then appealed.
The law does allow such a search. (Law does not protect physical evidence under atty-client privilege.) But Gore claimed it was done wrong. [And, in principle, no atty wants judges allowing LE to root around in their files, so there's that.]
Rusch was ultimately recused from the underlying case because of the search issue. Eventually the warrant/evidence was deemed legal on appeal (as far as I could trace it, anyhow). The defendant eventually took a plea (LWOP) to the charges of being the killer in a murder-for-hire plot, and ended up testifying against the wife who hired him.