What type of audio interface do you have? A really good audio/midi interface will reduce latency a ton.
I've used some of those programs. The timing is rock solid as described, but the user experience is nowhere near as smooth as something like ableton live or renoise. I recommend trying them out on an emulator if you can figure out how to get past the dongles.
If you are just syncing clocks then something like this is a better buy for you
http://innerclocksystems.com/New%20ICS%
20Pro.html
There are other options like this out there as well, the basic idea is to use audio speeds for your midi. Do you need just clock or are you sequencing synths? If you are sequencing notes on renoise and sending them out to multiple synths you should be able to achieve acceptable latency without any extra hardware.
Going from a modern DAW to an atari midi sequencer = bad idea IMHO. Something like maxymiser is for making chiptunes with the internal soundchip. Those other programs just do midi, so bye bye audio and midi on 1 machine (I'm sure you use audio for at least drums, right?) The ones that can do audio have archaic feature sets. Never mind no more vst's. If you want to use renoise and the ST at the same times that would be a workflow nightmare. Thats just my 2 cents. Leave the ST for the chiptunes, unless your Fatboy Slim and started out on an ST.