While I don't know if TGC will be plagued with the same issues as Slimcoin, there have certainly been fixes applied to Slimcoin that are not (yet) in TGC.

Slimcoin repo: https://github.com/slimcoin/slimcoin
ThirdGenerationCoin repo: https://github.com/TGCproject/ThirdGenerationCoin

I believe ThirdGenerationCoin cloned Slimcoin at this point (as it includes the earlier fixes, but not later fixes):
https://github.com/slimcoin/slimcoin/tree/a8be716fa426d7c021bca932ea3dd6ca103c481e

Comparing against the current versions:
Files in Slimcoin repo not in ThirdGenerationCoin repo:

path	difference(s)
src\qt\locale\*	localization files, inconsequential
src\qt\res\icons\*	media, inconsequential
src\qt\res\images\*	media, inconsequential

Files in ThirdGenerationCoin repo not in Slimcoin repo:

path	difference(s)
src\sync.*	not actually referenced
src\qt\res\icons\*	media, inconsequential
src\qt\res\images\*	media, inconsequential

Differences between files
In order to compare the files, the following case insensitive search&replace were performed first:

• "Slimcoin" -> "THIScoin"
• "ThirdGenerationCoin" -> "THIScoin"
• "SLM" -> "THAT"
• "TGC" -> "THAT"

Typos, whitespace, etc. are ignored.

path	difference(s)
README.md	inconsequential
share\setup.nsi	NSIS installer, not used
src\
base58.h	address format, inconsequential (SLIM: 63 'S' / 125 's', TGC: 66 'T' / 128 't')
bitcoinrpc.cpp	inconsequential comment lines
checkpoints.cpp	checkpoints and checkpointExists() function, Slimcoin only
checkpoints.h	checkpointExists() function, Slimcoin only
init.cpp	default ports, inconsequential
irc.cpp	IRC channel names, not used
makefile.mingw	for compilation, inconsequential
net.cpp	seed nodes, inconsequential
protocol.h	default ports, inconsequential
uint256.h	debug output, inconsequential (Slimcoin always outputs, TGC only if fPrintToConsole is false)
version.cpp	GIT commit IDs, inconsequential
version.h	version numbers, inconsequential
src\qt\*	resources, inconsequential
src\qt\res\images\*	resources, inconsequential

That leaves the following files where there are some major differences to the current Slimcoin codebase.

path	difference(s)
src\
db.cpp	major changes
main.h	major changes
main.cpp	major changes

As ThirdGenerationCoin was created on 2014/06/11 and not modified since, the following comparisons are made against the Slimcoin codebase of 2014/06/08.

path	difference(s)
src\
db.cpp	no difference
main.h	differences in coin supply and generation rate: const/define Slimcoin ThirdGenerationCoin MAX_MONEY 250,000,000 21,000,000 MAX_MINT_PROOF_OF_WORK 50 20 MAX_MINT_PROOF_OF_BURN 250 200 COINBASE_MATURITY_* 500 44 STAKE_TARGET_SPACING 90 180 BURN_HASH_DOUBLE 350,000.0 50,000.0
main.cpp	genesis block difference, inconsequential
main.cpp	debug output difference in LoadBlockIndex, inconsequential
main.h	genesis block difference, inconsequential
main.h	burn addresses difference, inconsequential* SLIM: SfSLMCoinMainNetworkBurnAddr1DeTK5 TGC: Tn5u46vuPfbdDJ2C154ysidVUXEn6jDtyC

---

So there's at least one thing you should do: review the code changes in Slimcoin since the clone point, and evaluate if they apply to TGC.

* One thing miners should do: request a change of the burn address to help alleviate concerns regarding whether or not somebody has the keys to that address.  See topic=613213.msg7359083#msg7359083 for more information.