I use Tweet Adder for nearly two years. There are a few issues of which to be aware.
The most obvious is don't update if you're on a Mac G5 or less.
Make sure HTTPS Only is unchecked on your twitter accounts.
Tweet Adder has been very stable, but it does freeze on me at least 2-4 times a month, so you do have to check it.
The profile search feature is working fine, but search tweets and targeting followers of a user are definitely having issues (At least on the mac version 10.x)
It's a good program. Was better when the searches worked 100%.
You need proxies these days. Make sure that you set times on the accounts under settings and build slowly tweeting only a few times a day. I do a lot of my offers in the thank you messages.
I posted this elsewhere, but I guess it's somewhat relevant here as well. If you need followers, I have a coupon code for exchangefollows for 300 coins, plus you can follow, like and plus for coins and they are fully exchangeable between sites. coupon code - "skin705" - it's good for plus ones and likes on the other sites.