Based on published specifications from the manufacturers.
The 2 antenna solution will give roughly the same gain (within roughly 1 db) on the hi-vhf frequencies. About 10-11dbs for either the 7697 or the 10-7-13 on those frequencies.
The DB8, however, gives you *significantly* more gain on uhf, especially on the higher end, where your weaker signals are (real 39 & 41 for cbs & fox)
17db gain for the DB8e & 11 db for the 7697.
Don't forget that a 3Db difference is roughly twice the strength. Or 1/2 the strength, depending on which way you look at it.
And that could make all the difference in reception. especially with trees.
The 2 antenna solution will allow you to tweak aiming towards Green Bay for either band.
Couple them with an rca TVPRAMP1R, which has separate inputs for vhf & uhf, low noise & an attractive price.
I agree. If you are pushing signal through 100ft of coax, you'll probably need a pre=amp.
Links to specs.
http://www.winegard.com/kbase/upload/HD7697P.pdf
https://www.antennasdirect.com/cmss_...s/DB8E-TDS.pdf
http://www.antennacraft.com/pdfs/Y10-7-13.pdf