I don't have any knowledge of the Tailspot blenny. It's similar to the midas but from their description it sounds like it tends to stay in the rocks alot. Midas blennies stay out in the water column alot which is what makes them so entertaining. They don't do much grazing on the rocks like alot of blennies since they are more zooplankton eaters. I've never had one bother sps or any other coral.

If you do go with a midas try and get one that is out of Africa. They are the hardiest and most colorful IME. Here's a link on them...
http://www.marinecenter.com/fish/ble...ygoldenafrica/

They cost a little more than the ones out of other areas but you should be able to get them cheaper than marinecenter. Their prices are usually kinda high. I think we usually sold them around $35-40.