Tony, let's address this in simple steps ... which is easily done by following your post:
"I currently have a Classic ID and feel it does a very good job in the field. Its as solid as they come."... No argument there. The Classic ID, as like most Classic series models, is a tough act to follow! Durable in construction and it has some very good field performance capabilities.
"I recently bought an IDX Pro that hasn't shipped as yet and am wondering if anyone knows how they may compare..."... Let me break that comment there to answer. They will compare very favorable, especially if they are set up with a similar discriminate setting and using the same search coil. The Classic ID, with its stock 8" coil, is a very good match-up for general hunting if there is not too much trash or building rubble, etc. For me, the best coil to compliment the stock 8" is the 4" 'Snooper' coil.
I always ran the Classic ID at maximum Sensitivity (unless there is chatter) and with just enough Discrimination set to reject a surface iron nail.
With the IDX Pro you have five (5) things to remember when setting it up, if you want to to operate similar to the Classic ID.
One, use the same Discriminate rejection level.
Two, make sure the Normal/Black Sand toggle is set to "Normal."
Three, make sure the Frequency Shift is set at the Factory Preset mark.
Four, use the same search coil.
Five, try to have the GB setting the same or very similar.
"... considering the areas I detect are not mineralized, just simple everyday soil."... Since early '65 when I started, and after hunting in many states from Washington to Florida and New Jersey to California, I still haven't found a site with ground that I would call "EVERYDAY SOIL!." Oh, I know that a lot of Florida is very "decent" soil or very "kind" soil or "not bad" soil compared with some very nasty, challenging sites, but I also know that there will be times you'll encounter some 'different' soil types, even down there.
"I do not expect to have to use any of the additional features of the IDX Pro in my area so it should be a pretty simple comparison between the two units."... Well, if you don't think you'll need the features of the IDX Pro, why bother? I really like the Classic ID, and it is working well for a half-dozen friends I have brought into the 'Classic Camp' this last few years. However, I personally use the IDX Pro because I DO like the added benefits it provides and I make use of them.
"Anyone have experience in side by side comparison of these two?"... Yes, as as I stated you will have very similar performance if they are both set-up the same and use the same coil. But if you understand the added benefits of the IDX Pro, you will have an upper-hand over the Classic ID in many applications.
Let me make one REMINDER, offer one strong SUGGESTION, and provide a little EXPLANATION about the IDX Pro.
REMINDER: Keep the Frequency Shift at the Factory Preset at all times. Try not to ever change it because it will shift the GB setting! This can be a real problem, especially since, usually, it will shift it more negative. If you're by someone else, let them make an adjustment, or else move out of interference range.
SUGGESTION: Consider sending the IDX Pro to 'Mr. Bill' Crabtree at Surfscanner Detectors for his modifications. You'll benefit a great deal by having the external Threshold control as well as an external Manual GB control. It is a very simple adjustment, but usually needed/helpful for perk performance if you [1] change search coils, [2] encounter more mineralized ground , and [3] need to adjust the Frequency Shift in order to work close to some offending RF interference.
EXPLANATION: The extra toggle should probably have been labeled "Normal" and "Expanded" or "Enhanced" because that is the benefits you can. When you toggle from 'Normal' to 'Black Sand' you're not adjusting the GB for some 'bad ground,' but simply expanding (enhancing) the lower-end of the Discriminate adjustment range. The benefit of having the expanded lower-end adjustment is that you will now accept ALL metal targets, ferrous and non-ferrous, when at the minimum setting and this is advantageous when hunting in any mineralized environment because there will be much less bias to the ground signal and it will easily pass along any metal target signal.
I feel the best 2-coil compliment form the IDX Pro is the stock 950 (for larger, open areas) and one of the 6