Hi ChannelGSW,
If they are a good match for you in terms of PPP … there would be no issues at all in terms of durability and microcoils are a very durable component.
Many of the forum members have purchased one of the microcoil mattresses made by Berkeley Ergonomics (which European Sleep Works used to carry before they began making their own similar line … see post #4 here) and have been very happy with them. A forum search on Berkeley Ergonomics (you can just click this) will bring up many more posts and feedback about various pocket coil / microcoil combinations. A forum search on microcoils (you can just click this as well) will also bring up many forum posts that mention them.
As you mentioned … I also think highly of European Sleepworks and the mattresses they make and I have had some very good (and long) conversations with Steven there who along with the rest of the staff there is very knowledgeable and helpful.
Phoenix