to renew or not to renew

[XLMonkey]

I'm not so much asking everyone if I should stay or go (although it's interesting to hear people opinions), my original concern was around IR35 and if staying at a client for more than 2 years had any more of a negative impact on that aspect.

Don't think that there is any impact on your IR35 status due to contract duration - there are lots of firms that have long term contracts lasting many years with the same customer. The thing to be aware of is whether you allow yourself to get lazy in the way you manage the relationship. As long as you are keeping a sensible audit trail that shows you are working on business to business terms throughout, there should be a problem.