For one, I mainly Relic Hunt iron plagued sites where I deal with dense brush, rocks, and building rubble. Smaller-size coils are what I have used th4e most since '68, sometimes putting a mid-sized coil to work in low-to-modest trash environments, or a 'standard' coil in more open areas and where I am looking for larger-size targets. I use the larger, or over-size, search coils when I have been Cache Hunting or for some contract searches [size=small](many of which have also involved searching for a cache)[/size].
I have the bigger coil for a Nokta FORS CoRe which is what I now grab for such hunting, and the operating frequency has worked well for me using it. The Makro Gold Racer is one of the finest detectors I have ever used for lower-conductive and tinier-sized targets. Meant for Gold Nugget Hunting it has no rivals I can think of that offer the features and performance it does. But the biggest coil I use on one of mine is the 5½X10 DD, which gets second attention since the other unit keeps the 5½" DD mounted full-time.
Due to the 56 kHz LF operation, I consider the Gold Racer to be best used for just those types of searches. Lower-conductive and smaller-size targets such as nuggets, or for thin gold chains, gold rings and other gold jewelry at locations where it has a greater chance for loss. I have used the Gold Racer with small coil for some Relic Hunting around some typical old iron littered RR ghost towns and a couple of stage stops, and it does well for me considering the operating frequency.
So problems #1 is I don't have the larger-0size search coil. #2 is the fact that I don't need it or have much need or applications that would call for that bigger coil on a Gold Racer. And #3 right now it that we still have a lot of snow left around, but the main hunt sites I enjoy, in the nearby Gold Mining camps and townsites, are all under several feet of snow right now and I probably won't have access until early-to-mid April. I will keep a watch for some field reports using it as it will be interesting to know what use they have for it. I know that it won't match the depth I can get with my 15 kHz FORS CoRe in almost any application where 'depth' is the important element to achieve.
Monte