The features I was looking for were automatic acknowledgement of registration and the ability to download a spreadsheet with delegate details. It does both of these but it required support and an upgrade to deal with multi line addresses which were being parsed into separate cells. The styling of the registration form apparently requires register_globals setting to be off, otherwise when you try to edit a previously entered style, it does not appear in the form, although the initial styling is still applied. Changing the register_globals setting isn't an option for me.
All support enquiries include a request for admin access to your site, which is not entirely satisfactory and I had to set up a mirror site for them to play with. Support responses were fast but on one occasion bordering on rude.
This has done the job I needed but for next year's event I'll be looking at DT Register, as the experience of using this rather expensive module was overall unsatisfactory.