I've had some first hand experience with EMP and I can say that their line of evacuation products are spot on.

I'm not sure if the reference to IOSH is an endorsement but they have won an SHP award for one of their products and from a personal perspective (working for a large transport company in the UK) I'm very keen to get the 'Goods Mate' into our workplace to alleviate a large number of the issues in relation to manual handling up and down stairs.

They had a stand at the H&S Expo and we've had them in our workplace for a personal demo of what their products can do. If you're interested I recommend giving them a ring, very helpful bunch of folks.

Another issue we have had with evac chairs is that there is only one (sensibly) but if there is more than 1 person requiring the Evac Chair what do you do with the other people? You can't take it back up for the others because it's occupied. Also often it is a wheelchair user that requires it, what do you do with their wheelchair? It's often too heavy/large to take down a flight of stairs.
Another issue I've come across is a wheelchair user who can't be moved due to his disability. Moving him would kill him as the chair is designed to support his body and has an oxygen supply (to enable him to breath) installed in the chair.
Evac Chairs look good but not very practical in theory.

The Fire Risk Assessment must look at evacuating both staff and the public if they use your premises. If you have more than one staff member with a Personal Evacuation Plan that identifies the requirement for an evac chair, then I would suggest the fire risk assessment should identify the minimum number required. Yes, in the ideal world, fire lifts are the preference but lets not forget that people were evacuated successfully from the Twin Towers using evac chairs. Its back to "the competent person" again and that competent person talking to the right people to ensure the FRA is both suitable and sufficient.