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Autoguiding programs calculate the centroid of the star so whether they are sharp or not may not be so important. I do find though that if I start an autoguiding sequence the first thing I do is select another star. Especially one that is a bit less bright and tighter. It usually works and I get a significant improvement.
I have used a 720nm IR filter on my guide cam before. I haven't used it in a while.
As I recall it did help somewhat but it also dropped the luminance of the guide stars a lot so it was really only practical when you had a bright guide star which you can't always get. M104 for example has hardly any guide stars near it.
So unless you are prepared to remove it and put it back on depending on the guide star availability its probably not worth it.
You'll get a bigger gain by doing a more perfect polar alignment with T-Point.
Also I believe you raise aggressiveness of guiding when the seeing is good not when its poor. If seeing is poor you end up chasing the seeing and overcorrect. When the seeing is good you can correct more aggressively without chasing the seeing and overcorrecting.
On my high quality mounts (Software Bisque PME and AP1600) I use 6 second guide exposures. When I had a Tak NJP mount I used 1 second. 6 seconds works better as the corrections don't overcorrect as the mounts periodic error is low. Of course that will vary with the mount but I think its most likely the weaker the mount the shorter the guide camera exposure time.
Greg.
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