The 8450 is discontinued, but in it's time it was one of the best servo's on the market. There's no reason why it wouldn't work very well today. Click here for the spec's
. The newest JR is the 9100S
. If you're going to upgrade for offroad, any transit time of ~.06-.15 will be fast enough; and depending on the vehicle, Torque can be from 80-100oz/in for electric 2wd, anywhere up to 300+ oz/in for 1/8th Truggy.