I guess i'll jump in here...

Probably the best qualified to answer is Jay over at J Good in http://www.jgoodin.com/ as they have purchased Evolution and then Interprise. I mention Jay as he is listed as a happy customer on the evolution site - http://www.darwinproductions.net/whatotherssay.aspx

Best bet is to demo both products and see which one fits your business best. A perfect fit for one business may not be a good choice for yours.

Re Interprise Suite support being more expensive than postbooks:

To clarify - Interprise Suite phone support and maintenance (free updates and upgrades) currently runs about $360/yr per user. Compare this to PostBooks http://www.xtuple.com/pricing

Interprise Solutions Application and Source code training runs $750 for a week – PostBooks is $3000.

http://www.interprisesuite.com/Confe...7_LA_About.htm

http://www.xtuple.org/?q=node/4298