ESP is mainly Vipec and Haltech and they like em for good reason.
Although they say
"We are agents and tuners of ViPEC, Haltech, HP tuners VCM Suite, Herrod SCT Flash box, Wolf Ecu, Power FC, Emanage Ultimate and Blue. We also have a large amount of experience in Motec, Autronic and Microtech ECU’S"
Your after an Emanage Ultimate and I suspect they are right. I'm sure also their prefrence is with Haltech and Vipec as they are good and yes it may be more than you need.
So I suppose you have what you have and they should work with that.
Have you given much consideration to NIStune and Autotech if your on a budget and dont want/need all the bells and whistles of the Haltech, ViPEC (G4).