I'll tell you what I know about spool gears- they are very bad if you plan to run at anything other than a crawl, and on road. Various people report continually busting cvds and slider shafts since there is no differential anymore, and you still need to shim the ring & pinion correctly or else the two gears will not mesh perfectly and grind eachother down.
Its mainly built for street use. its been lowered and i have the rc trix sway bar kit to hold it to thee road. Do you think the stock screws on the spool will hold up? I have 2mm steel screws.