I have an older model Vector which is a front entry (diagonal zipper)
DUI suit.

I personally prefer an easy self-donning suit rather than the shoulder
entry models which depending upon your flexibility can also be
self-zipped and unzipped.  I can zip and unzip most shoulder suits
I've tried, but a buddy makes it easier.

I can get into my front donning suit real quick, which is handy both
on those real hot air temp days and the super frigid ones .

That said ... with a $700 delta ... being cheap ... I mean thrifty ...
if I was buying new I'd lean to the shoulder entry  if I was sure I
could fully zip and unzip  the suit without assistance (and preferably
without helper tools).

If money wasn't an issue ... my personal ease of use pref is with the
front zipper since I often dive solo (though not always alone).

Guessed positive of a shoulder entry - shorter zipper should mean less
to go wrong over time, less lubricating and less cost if you ever have
to replace a zipper (which I haven't done in the 15 years I have had
my suit) .

another thought  ... in case a zipper gets snagged a front zipper can
easily be checked and resealed.  Then again, to be fair, a front
zipper is probably more prone to getting snagged due to it's location
if you lie down while working (happened to me only once so far)

You should attempt to do a try before you buy of the 2 suits if
possible.  
            - Ed