I have had good results with the spectra also.  I'm using it for 15m x 2-3 times a day in addition to noogling.  I'm using PM on my nipples as lube, then sit back on level 12 and let it works its magic.  I can actually have a hands free orgasm from it if I skip a day or two.

I started with the 13mm inserts, and currently using the 17mm & 19mm inserts.  Both give a very different sensation. 

The inserts came with a nice nipple measuring card.