Glenn is right. GBBs can be skittish but so can any tarantula. They have different personalities. Chilean roses are supposed to be calm, docile and perfect for beginners but mine is really aggressive and rears up allot in a defensive display. Red knees are a great choice and it's true that they grow slowly but that doesn't mean they aren't brown for a long time. This Red Knee has only just turned a year old and already has plenty of colour. When I got it a year ago it was less than 1/4" and was only £7.99.

Edit: 3/4" will be more than 2nd instar.