I am firm believer there is no free lunch in the world. Open...

I am firm believer there is no free lunch in the world. Open source development, or any kind of software development is expensive exercise, it makes sense if you develop software for emails, photos, social media, where you can quickly attract a volume of users (assume you have a good product), attract advertising dollars or potential other sources of revenue.

But SMSF is a niche market (some people referred as cottage industry, fragmented among mostly hundreds and thousands of accountants, you cannot easily to achieve economies of scale compared to social media or photo sharing), financial services software involves a lot confidential and personal data to have your TFN, bank account details entered into a free accounting software, I am not sure you will be entirely comfortable to do that.

As a SMSF trustee, if you are component enough with certain business acumen and likes control, you can pretty much look after the investment side of running a SMSF. However there are 3 things you probably need outsource as a minimum:
1) Auditor, even if you are a qualified auditor, you cannot audit your SMSF. All SMSFs have to be audited prior to the lodgment of tax return.
2) Actuarial Services: especially for people over 55, reaching preservation ages or near retirement, to maximize their benefits, they will set up pensions need actuarial services.
3) Tax Agent Services: get someone lodge the return.

That's assume you know your trustee obligations and compliance requirements etc. However how many trustee can put their hands on heart to say I know how contribution cap works, bring forward rule, pension limit, preservation, capital gain tax, in-house asset rules, dividend streaming, supervisory levy, SuperStream, div 293 tax, contribution split, rollover, PAYG, GST, lump sum, conditions of release, etc work...

That's why vast majority of SMSF trustees will engage an adviser/accountant/smsf administrator to do above for them, while they can focus on investments.

This is where Class and indeed other specialised SMSF software fills the gap, they make everything other than investment easier for the accountant/planner/smsf administrator to do these compliance and administrator work.