Idlemaster and SAM: Safe to use?

If you can edit a text file, you can use ASF.
I never got banned for either of them.
With ASF it's impossible to accidentally start a VAC game. With idlemaster it can happen.

"heard conflicting tales of people getting VAC banned"

Where ? U wont see any threads of people getting that problems :P
Edit: And just to be safe, I dont use them when playing VAC games and just farm cards when i sleep :D

The interface takes a bit longer to get used to for ASF, but it's a much better program. There's no point to using IdleMaster anymore since it's no longer supported. Doesn't matter if you're idling 1 account or multiple, go with ASF.

I had issues with IdleMaster constantly disconnecting me so I switched over to ASF a few weeks ago.

ASF is actually friendly as hell. I was scared of it too. But now I absolutely love it.

ASF is much less user-friendly than Idlemaster and is intended for larger-scale use anyway.

Less user-friendly - definitely, I expect from my users to read, you can configure IM without that. That's partially because ASF includes shitload of options, and partially because I don't want to make it more friendly - there is no need to.
Larger-scale? No. ASF is designed for supporting any number of active accounts, which doesn't mean that it's any "less suited" for 1 account instead of 10 of them. It supports any number of accounts, doesn't matter if 1 or more.

IM is deprecated and not supported. ASF guarantees being VAC-free and is not using typical emulating of played game as SAM or IM, but uses it's own built-in steam client that sends legit requests to steam network. Getting VAC because of IM is very unlikely, but there is a chance, be it because Valve suddenly decides to fight with idling, or because their system intentionally or not, starts detecting DLL library used by IM as malicious. It is hooking DLL into a process and communicating with Steam through it, regardless how safe or not that is. And you know what's the worst? The fact that NOBODY cares if you get VAC or not, because developer doesn't support this program - you're using it at your own risk, and nobody will help you if anything wrong happens. If you really care about your safety, then that alone should be enough for you to stay away from it, and it's not even a main concern.

More and more people migrate from IM and other tools to ASF every day, my group has over 33.5k members at the time of writing. I'm more than sure that you can find many of your existing steam friends there - why not ask them what they think about it?

I always repeat that every user has his own choice and can decide himself what to use, and if use anything at all. I don't have any profits from larger fanbase, I don't have any reason to convince you into using ASF either. Keep one thing in mind - I created ASF because IM didn't satisfy me. It didn't run on Linux, it didn't guarantee being VAC-free, it didn't have support for steam events and switching game immediately after it's farmed, it didn't have offline farming feature that finally stopped my friends asking me if I'm playing or idling. IM was breaking constantly, steam client was breaking constantly, and I simply had enough of software that doesn't work. Now ASF didn't only fix all of those flaws, but nowadays includes even more neat functions, such as choosing optimal cards farming algorithm, StreamTradeMatcher integration, and many more things which are impossible for IM to implement, mainly because of the idling method that differs IM from ASF.

You can ask if IM is really that bad - no. Majority of issues above are because of how IM works, not because it's bad as a software. I decided that it's final time to move from that poor method of steam game emulation into something that can interact with the steam network in the way I want. And that happened half a year before IM got discontinued, ASF wasn't created yesterday - it's here for nearly 8 months now, being used by thousands of users every day.

Therefore, if you ask if IM or SAM is "safe", and you don't consider using ASF instead of IM, which is much safer and still supported, then it's like choosing between jumping from 10th floor or 9th one, instead of taking an elevator. To me such question doesn't make any sense, but as I said - I'm not deciding for you.

Above was written from developer perspective. User perspective is much simpler - ASF is safer than IM or SAM will ever be, and only that should matter for you. If not, look at other users and their opinions, those are not paid reviews, those are people who tried and never turned back again.

Definitely use ASF instead of IM. I postponed switching to it until IM stopped working for me completly simply because I thought it was too complicated (for me) to configure and use, but honestly, it probably took me less than 5 minutes to set it up with 2 alt accounts after searching for what I have to do in order to make it do what I need it to do.

As for SAM, I don't know your achievement situation, but I wouldn't really recommend it. I got all the in-game achievements for a game (Soul Gambler) before the steam achievements for it were implemented and I thought about activating them, but I don't think it's worth the risk. Plus, I have friends on steam that have achievements that they "got" at the exact same second, and it's way too obvious.