BruceB wrote:Unless there is a thread similair to this I would be interested in knowing the relative merits and demerits of each the price bracket the sit in.
I'm not sure what you mean by this. You might get more of a response if you post this question in the "espresso machines" forum.
That being said E61 is just the format of the group. I think that you may be really wanting to know the options besides heat exchangers in espresso. Most HX machines have the E61 format. The three general classes are single boiler, heat exchanger, and double boiler..these describe the internals of the machine primarily and how heated water is produced to brew and control the temp.
Most entry level espresso machines are single boiler (Gaggia Classic, Silvia) which have very good temperature control in general. Add a PID and you can be really in business with temp stability.
HX is probably the next level up in temp stability and cost. Will significantly improve work flow to steam milk if that is important in your drinks. Single boilers you'll have to change the temp from brew to steam and that can take some time. You also then have to purge the steam so that the boiler doesn't dry out for most entry machines.
Here is an article on SB vs HX but there is lots of discussion around
http://coffeegeek.com/opinions/javajim/07-14-2003Double boilers have a separate boiler for steaming and brewing and are usually another step up in price in general. All commercial machines are DB.
Does that help?