No, it would not increase anything.
The N is not based on extra power but on crafty arrangement of Antenna's Input Output (thus the term MIMO). So when it works with G it is plain G.
Draft means that there is No agreed upon standard, but rather an agreed upon arguments. Thus there is No guaranty that when the standard (802.11n) comes out the final type of hardware the Draft devices would be compatible or upgradeable to the Standard.
E.g. D-Link's Data Sheet of its expensive flag ship Draft Wireless Router states:
"This product is based on IEEE draft 802.11n specifications and is not guaranteed to be
forward compatible with future versions of IEEE 802.11n specifications. Compatibility
With draft 802.11n devices from other manufacturers is not guaranteed. All references
to speed and range are for comparison purposes only. Product specifications, size and
shape are subject to change without notice, and actual product appearance may differ
from that depicted herein".
P.S. This does not appear on the Device's Internet page, but in a small print on the Downloaded Data Sheet.
<a target=_blank class=ftalternatingbarlinklarge href="ftp://ftp10.dlink.com/pdfs/products/DIR-655/DIR-655_ds.pdf">ftp://ftp10.dlink.com/pdfs/......655/DIR-655_ds.pdf</a>
The above is Not unique to D-Link it encompasses all the "Drafts", at least D-Link is honest about it.