I use Sonarworks Speaker and Headphone cal software. I have not used ARC or ARC2 since I started using Sonarworks. I highly recommend both! Try the demo and use your ARC2 mic, I think you will like it!
I made the initial change to Sonarworks because ARC2 only allows one instance using a different correction curve.
If you have more than one set of monitors and want to have ARC2 on multiple buses with different correction curves you can't do it. The original ARC would allow this but not ARC2.
When I made the change over to Sonarworks I was blown away by the measurement process that only takes about 20 minutes total to do a Full measurement session. No templates and tedious moving things around to measure. I use to spend an entire morning setting up and doing a measurement session with ARC2.
When I first used it I noticed a big difference in the sound as it no longer sounds like it is thin, hollow, harsh, and highly filtered as ARC2 always did. It does fix my 125-250Hz issues yet does not thin out the mids as ARC2 did. Things sound defined and mixes translate as well as ARC2 did.
I did upgrade the Speaker correction software to the HD version and I can see some difference in the correction curves when taking more than 30 measurement points but I can't really hear enough difference to warrant the cost unless you find it on sale. YMMV.
Also, If you use phones much, and have a set they offer a correction curve for, you really should give it a try also. I never use phones without it anymore.
Last but not least, Sonarworks support and service is Great! They respond quickly and are willing to Listen to their Customers, I have never had a bad experience with them.
Kind regards,
Rick