>> ... Icom 746 Pro using the SM-20 into a W2IHY Dual Band EQ/Gate ...
Very nice setup, indeed.
>> ... pretty happy with the results ...
And I am sure your received audio reports are fine, too.
>> ... Heil PR-781 or Pr-30?
You already have a very good setup. "Improvements" by upgrading to a Heil are not going to be as noticeable for you than someone with "lesser" audio equipment.
>> ... Have also seen opinions that the Heil line is overpriced ...
Usually from ignorant folks ... or folks with poor ears. Or folks who just do not care about the quality of their audio.
>> ... just as good results with other mics such as Behringer, Shure, Electrovoice, etc.
The amateur radio market is a little different breed than that live/pro audio market. Bob Heil knows both industries very well. I believe he is still the only manufacturer of audio equipment to inducted into the Rock 'n' Roll Hall of Fame. And he is a ham, and knows ham equipment. I use Heil mics for podcasting and VOIP sessions ... but I also use a Sennheiser mic for field interviews.
>> ... Am I wasting time looking to replace the SM-20 or is it worth a look?
There's a degree of satisfaction knowing that you are putting out excellent audio. Many may not appreciate it. But YOU will know ...
Clint Bradford, K6LCS
P.S. - "Heil is over-priced?" Here's a mini-review of the Heil HM-12 - retailing for
well under $100 ... http://www.k6lcs.com/k6lcs/HM12.html