Fitting for the head or fitting for the legnth? Or both? I have 3 putters that I rotate in and out based on the course I'm playing. Odyssey 8/33in, Odyssey 9/33in, Ping Karsten 2/34 in. I mainly rotate the odyssey putters just to keep my head clear and I use the Ping on courses with really slow greens. I've never though to be fitted though, just go with what feels right.
I went to club champion and went through a putter fitting on the SAM machine. It was worth the time and money.
I not only got to see my stroke from the time I started my stroke and through impact. It helps understand that we all putt on some kind of an arc. Even if we think it's SBST, there is a little arc still there.
For me it helped understand the proper loft I should be playing, length and most importantly what type of head shape fits me the best.
I highly recommend it if you have the extra $$ to spend. Well worth it imo.
@ErikFb4da never have been fit but I suppose through my extensive buy/sell of putters I've kind of found out what works for me and why. My guess is that if I ever was actually fit my results would be the same as @MikeG_74 based on what kind of putters he plays and the fact that we seem to have the same tastes/preferrences.
At one time Odyssey had a pretty good online putter fitting tool you could use and get you close. It was spot on for me because if I try any other style or length it just doesn't feel right. I don't know if it's still on their website though.
For me it was the feel of the putter. I went with a blade for a while and then mallet. I keep both in my bag: depending on the weather and greens determines which one I use. All I knew is that a 38" shaft seemed way too big, 34" too short and a 35" seemed ok. I think I am more about the grip these days. Right now I keep the long original grip on the 2 ball Fang tank and for my blade I have a custom pistol grip SuperStroke.