1) Carry gun is a Colt Defender 3" and looking to purchase full size mags, Reason for getting full size mags is have two other full size 1911 and would like to use in them as well. Also they carry more rds

Plan to carry the compact mag in gun and full size as a spare.

Is this a good/bad idea using full size mag in a compact 1911?

2) Leaning towards the Wilson Combat EMT mags but there many EMT options. I have no experience with them but in other threads they well received.

The different versions, standard EMT, EMT HD+P and EMT-V. Price roughly are $34.00, $45.00 and $54.00

Have seen people talk about the EMT and EMT HD+P but no one talking about the EMT-V so far.

So is it worth it to go more expensive versions?  

3) Base Pad there are several options and sense this is for CCW thinking about steel Lo-profile. However some of the other options look nice too.

Another concern is the Lo-profile is steel unsure what type of steel. Carry IWB and at 6:30 position and it gets very sweaty.

4) Finish: they have a option for finish for EMT & EMT HD+P the Black Fluoropolymer Finish. Is this worth it?

Currently my mags will get some rust on the outside that faces the body but doesn't rust on the inside. I try to take of them but out fishing, mowing and etc there is sweating.

Don't want to get the finish and it comes off after a few years.

is the finish worth it?

The EMT is their 8 round magazine. it was designed as a 8 round magazine from the ground up.
The metal is alittle thicker on the feed lips and the spring is square to be stronger.
It will also stick out the bottom of a full size gun about a 1/4 inch.
I have used them on my carry Commander since they came out.
So I have 8 in the mag and one in the chamber.
The ones I like the best is the EMT with the lo profile steel or alumninum base pads.
They are a bit more durable than the plastic base pads.
As far as the finish I don't think the black finish wears off fast, but the plain stainless feels slicker, so I would rather have that.
Hope this helps

I run checkmate exclusively. 7 round flush and 8rd with flared base. I do carry Wilson 10rd mags as a reload. Checkmate makes ruger, sig and kimber 1911 mags. They can also be found as straight up checkmate. And on eBay from joes1911mania

You must guard against over-insertion of full size magazines.  Here's a link that may be of interest in this regard: LINK.

Do you mean "ETM" - Elite Tactical Magazine?

Wilson, like all the other magazine manufacturers offers plastic replacement base pads that allow full size mags to be used in compact frames.  The problem with these replacement pads is they have a single extended piece of polymer that runs up the front of the mag to make contact with the frame.  In the heat of the moment and the adrenaline is flowing, it's possible to snap this extended piece in two.  Some magazine manufacturers tack weld a piece of steel to the front of the mag tube to prevent over-insertion.  I've seen these break off during matches which results in a slide locked pistol getting totally jammed up and taken out of service.

As you say, steel or aluminum base pads are more durable but I'm not sure Wilson uses these materials to make the base pads that allow for the use of full size mags in compact frames.

What is really needed are base pads that make contact with the frame at the front and both sides simultaneously.

I would caution you against fullsize mags in an officers sized frame, unless the mags you are using come with an over insertion stop / sleeve. That would be the only thing stopping you from over inserting the mag and damaging your ejector.

To piggyback on what steve said, those overtravel / overinsertion stops on the mags can and will break, usually at a bad moment.

Stick with your flush fit 7's

Yup.  Being fully aware of this, the oversized base pads I modified contact the frame on all three sides of the pad.  There's next to no chance of all three sides breaking at the same time and causing an over-insertion problem.  In fact, I doubt pounding on them with anything less than a 3lb baby sledge hammer would cause them to actually break.  Check out the LINK.

That does look nice Steve.

Thank you all, there has been much helpful info.

When everyone started talking about over inserting mags it kind of rang a bell. I did that on a AR15 once and took a bit to get undone.

Now keep in my mind if the back up mag is coming out it is a stressful situation.

I am going to stay with the compact mags for the present time. Going to look over the full size mags and adaptor bases and test them over time. The ones Steve uses look promising.

So for compact mags that fit flush the Colt ones have been very reliable. Any other suggestions for compact mags?

My SOP is to never load more than 7 rounds in a flush fit magazine even if the manufacturer says it'll hold 8.  That'll give you a total of eight rounds - 7 in the mag +1 in the chamber.

Any of the major manufacturer's compact magazines should work fine.  Tripp, Mec-Gar, Check-Mate, Wilson, McCormick, Metalform, etc should be your go-to.  Everyone has their favorite magazine.  My favorite is Check-Mate but there's nothing wrong with the others.  Sources include Top Gun, Thunder Mountain,  and Greg Cote.  I recommend buying a single example from several manufacturers to see which one your pistol likes the best then get more of that one.

Here's some more reading that may be helpful to you: LINK.