I don't have any specific experience with these units but I do know that you need to be sure you buy the right unit for the type of water you have. For example, if you drink well water, one particular unit may be better suited to that task than one that's mainly installed for public water. Have you had your water analyzed? This would go a long way in getting the RIGHT unit. For about $25 (I think), you can have your water analyzed. In my opinion, this is money well spent if you're going to invest in a unit that's a few 100 dollars in cost.
And while your're at it, be sure to look into the cost of filters and such. THAT could be costly, model dependent. Soooo, if you want you water tested, contact any Well Company or Public Water Utility Company for testing sites. (I do strongly suggest you have your water analyzed no matter if someone 'tells you' it's OK. House depending, there may be lead in it. The only other option is to compare the units on your own. You can visit My Favorite WEB Search Engine and peruse the links. There are about 200 of them so you'll have to 'filter out' (no pun intended) the links that are 'useless'.