Is there a any reason to go with all the same companies or modles of rods and reels.  What are the pro's and con's if any?

Consistency.

All of my combos feel the same with the same reels and same rod builder

Im going with st. croix legend tournament rods. Daiwa team X super-tuned bait casters and shimano stradic spinning reels. Any suggestions?

I'm looking for a new crankbait rod and the only way to get the st croix is to order it without feeling it first so I thought about changing to the G loomis for only the crankbait rod?

If you can feel a loomis rod in the store i would go check them out. Then you can make your mind up on your own. Ther is no real advantage to having them be all one company on the rod.

The loomis will probably feel a little lighter.

Med-Heavy Loomis=Med. St. croix in my mind

I have 2 G Loomis crankbait rods and love them.

Consistency.

Exactly!

It is very useful to know what to expect from each piece of equipment you use, especially with reels. Knobs at the same place, drug settings similar, weight identical, etc. Even with rods, you will often notice that although two similar length rods (from different manufacturers) may be labelled "MH, fast", there may be a significant difference that affects your particular type of fishing.