Originally Posted by niznai
Yeah, I was wondering, why would you throw away all that engineering you paid for by buying a T4/15 by just skimping on the servo. I mean a 9551 (or current versions) is not that much more than 50 pounds if you get it on the internet and a heck of a lot better than the rest of the budget servos. In all likelihood the servo will stay with you for many years after the chassis is obsolete, so it's a long term investment, worth doing it right the first time.
9551 is smooth because it's slow. Low torque too. I've used one before. Recently gave it away to a friend. They aren't bad. They are precise, but they're slow. No getting around that. BLS551 is marginally quicker. Slower servos will be smoother. I prefer faster and stronger. You just have to be smooth with your steering inputs, because they do what you tell them to instantly.
I'm not on some tight budget. I could use any servo I want in my cars. I chose Xpert PI-3401-B because it has the best balance of speed and torque @6V of any low profile servo I've seen so far. They just happen to cost a little less than most of the big name manufacturers. You could give me a BLS551 or a KO RSX One for free and I might keep it for backup, but I would not swap out my Xpert servos for something slower and weaker.