These tips are just ideas, not facts. I think that JA:DG is an outstanding game already, but these custom editors make the game that much more fun, especially this profile editor.
It's not that I could do anything better, but I like to do things my own way:

Create only one or two excellent and very cheap mercs (similar to the style of the IMP editor of Jagged Alliance 2). Give them extra stealthy attributes. Keep the rest of the mercs the same or nearly the same. Lower Scully's, Mike's, Len Anderson's, and Magic's salaries a bit, too (by 20-50%). This might be a more fair way of changing things while keeping nearly the same level of difficulty in the game.

Get rid of all the negative characteristics of all of the mercs-- the stubbornness and forgetfulness of some characters never really added much to Deadly Games, in my opinion... if anything, these things complicate and weaken the game (that is, they drive me nuts!!)

Reverse the abilities of the mercs for a change: make Sparky the top marksman and Mike a very poor one, for example. With this approach, you can play the game using different mercenaries, instead of relying on your usual favorites. The normally lousier mercs have more eccentric personalities... why not turn them into a winning team? It adds a lot more variety and fun to the game!

It almost goes without saying that it helps to save many different versions of the prof.edt file (name them prof01.edt, prof02.edt, etc. and rename your desired file "prof.edt" or keep each version of prof.edt in separate folders). Save your original prof.edt file, too (or extract it from your CD if you really screw things up)!

Mortars and grenade launchers are the spice of life, but don't forget plenty of shells and grenades (and five-pocket vests to carry them). Use a few characters that you don't like, make their salaries very cheap, give them a ton of complete grenade or mortar equipment, and then fire them right away after taking all of their weapons, if necessary, heh, heh!

Chainsaws, chainsaws, chainsaws... replace any knife with one of these! Vroom!!

A few alternate nicknames that I like (then again, I'm slightly deranged!):

--change Dr. Mark "Needle" Kranhuim to "Eyeball" Kranhuim

--change Corporal Len Anderson to 1st Sgt. (or Sgt. Major!) Len Anderson (and raise his marksmanship, too, while you're at it!)

--change Koolhan's nickname to "Dr. Kool" :)

--give Col. Leo Kelly a nickname: Leo "Kick-Ass" Kelly, as he says himself!

--give "Mike" a last name: Tolken! (Elroy's brother??)

--change "Scully" to "Oy!"

--if you're not bright enough to create a merc named after yourself, well... dang, you must be modest or just plain dumb! :)

--I bet you have more than a few cruel and silly ideas of your own... I'll let you and your imagination run wild... and please don't tell me about it! I think I have enough problems and strange ideas the way it is. Remember, you're dealing with someone who is still enjoying a DOS game! Well, all right, if ya gotta, ya gotta... put your nicknames in the forum, but be discrete about it! Ya don't wanna air your dirty underwear in public now...