I am using MFJ hamsticks for 20m and 40m bands in dipole configuration(s), i.e. installed in MFJ-347 mount. Here is the first post in this blog on MFJ-2220 and MFJ-2240 dipoes on 38ft/10+m Max-Gain fiberglass pole I use. In a word, 20m dipole works well for me. I use it to make DX as well as stateside contacts. It is not beam antenna, it has inherent loss and not all power makes it to the far field, but it definitely works. It also has some directivity at the height I use it (again 33-38ft, i.e. a little more than 10m). As for 40m dipole at this height, it doesn't work very well, and finally I became curious enough to overcome my laziness and did some modeling in 4nec2 (4nec2 is popular free antenna modeling software -- get your copy).