I had both Rider & Spacer. I don't like Rider coz it is too heavy. For tempo & LSD, I prepare Spacer. But for trail run, I will use Rider.
Agree much with Alex ching ... Rider is really heavy. So it is my training shoe for LSD and tempo. Spacer is really light and feeling w/ road is really good, it is good for race but i found life of spacer is really short if you kept wearing for training... i guess could be only last for 3-5 months....