Sagepay is absolutely huge in the UK with more businesses than ever using them as their gateway.
I too had issues and could not get things right using server and ended up using the SagePay developers kit to integrate the direct method into the site. I have to say that the direct method is far better and looks so professional.
If Webassist really want to gain more customers they should consider introducing Sagepay direct as an option cos their product would fly off the shelf with developers wanting to use this method.
I am a developer with 12 years experience in the industry and have been a Webassist customer for a few years and their products absolutely rock!! i couldnt do my job effectively without them, and for me, as more and more of my customers are demanding Sagepay direct integration I would love it if Webassist were to introduce this in a future release of eCart. I would even be willing to pay extra for the incorporation of this facility (I invested heavily in ALL webassit products prior to the subscription service) as it would speed up development time hugely.