I am also on the hunt for a helpdesk and asset management system. Lansweeper is tripling their price, and Solarwinds WHD is just dated and buggy. I looked at Genuity, the price is certainly right, but after a trial my techs decided it doesn't have the capabilities we need. We are looking seriously at FMX (gofmx.com) after a recommendation from a colleague, but it is kind of expensive. That said, anything I've found so far has been more..
I'll take a look at Halo.
Shaun, have you looked at FreshDesk? I'm not sure if it fits all your needs but it gets recommended a lot around the web.