If a few big projects come through business wise, I would like to do some panel update.  Now I have an approach certified Garmin 300XL.  This little monochrome unit does everything you need it to do, and a bonus is for each data base update, I simply take the card out of the 300XL, put it in the 155 below it, update that one and put it in the 300 XL.  The 155 is a month old, but never an issue. I use it mostly for DME, groundspeed, ETA, etc.  That saves the price of one subscription.

But I would like to go color and bigger, given my 55-year-old eyes.  I am thinking of installing something like the MX-20 or the Avidyne 500 to have a nice big display. I have 3 options to send the data to it, increasing in expense:

1.  Put in a 430 as primary and keep the 300 XL as backup. Find a good home for the 155.

2. Put in two 430's find homes for both the 300XL and the 155.

3. Go with a 530 and a 430, find homes for 300XL and the 155.

Lot's of tradeoff's here. 

Is it dumb that, going to this much expense and trouble, to keep the 300XL? 

If you are having a big MFD anyway, what does the 530 get you that the 430 does not.?

Would it make sense to save enugh $$$ to go with a new WAAS 430 for primary and a used standard 430 for backup?  etc.

Are there similar data card advantages with two 430's or has Jepp made sure you can no longer use my approach (revealed to me by Dr. Darling, thank you very much.)

Very interested in any and all comments and suggestions. 

Scott Sedam
N4843W, '77 114
Willow Run (YIP)
SE Michigan