Experienced juice faster here :o)

OK...with blended fruit/veges you WILL be getting health benefits. Lots of vitamins and minerals plus a ton of fiber which is great for a bowel cleanse.

You may not get the same concentration of vits and mins as if you were purely juicing (it would be hard to consume as many with the added pulp/fibre) but you will still consume more than you usually would I expect and this will definitely have health benefits!

The thing with fasting, taking only liquids (no pulp), is that your digestion shuts down after a few days and the body switches into a "housekeeping" mode....putting it's energies into healing and cleansing. Also...the tummy rumbles and intense hunger disappear after these first few days making fasting reasonably smooth sailing until you feel you want or need to break it.
You need to understand that your digestion will not switch off with smoothies. However, your body will cleanse a whole lot more than if you continued to eat say wheat, milk products, meats...refined stuff (or whatever you normally eat!)

If a smoothie cleanse is what you're up to right now then why not go for it??
Apart from that it WILL have health benefits it may be a great introduction to some of the challenges you'll have if you embark on an actual fast later on when you have a juicer :o)

One caution.....mixing fruits and veges. This is ok with juice but I believe if you use the whole fruits and veges some combinations may be a little difficult to digest (due to the fiber maybe???). Look up food combining at that may give you some pointers!

Best of luck to you :o)