Regarding macro / activity, the OFA 6 also have Macro & sequence functionality and supports discrete Power & Input programming. In fact the OFA 6 has a bonus because of its Home Theatre Mode. However, there are important differences between the Harmony 525 and the OFA 6 series:
Look: the OFA 6 looks very dull & simple, even a Granny can use it. In fact my Mom (65 years) & Dad (71) use the URC-7560, which is the older OFA 6 version of the URC-7562. I also have one, my brother has one. And we haven't used the original remotes of their AV equipment since then.
The Harmony does have the Geek bonus because it is impossible to set up without computer and connection to the Harmony web site (and Logitech's permission, some people wanted to set up a 2nd hand Harmony and had no joy, the first owner already used the right to use).
Ergonomics: the H525 casing is crap, but you can buy the more expensive 555 which is OK, the OFA 6 has by far better ergonomics! Because of the shape of the buttons, you can feel & press the right button (or start the macro / sequence you want) without looking at the remote. Also the rubber strips & curved shape make the OFA 6 a pleasure to use. And you can hide functions you do not want to use that often or want to avoid that are pressed by accident (e.g. tuning in Channel functions) under the flap.
Built quality: just look on e.g. remotecentral about the (lack of) quality of the Harmony 5xx and 6xx series. Statement of the Harmony support: life is 10 years devided by number of devices. So if you use 5 devices, it won't last longer than 2 years. I bought my OFA URC-7560 in 1999, have used it in these 8 years for 5-7 devices (the OFA does allow you to merge functions from different modes) and it is still working.
Battery life: Harmony 525 up to 4 months - OFA 6 app. 2 years with only 2 AA batteries
BTW the more expensive Harmony's have a charger, you can charge, charge, but do not forget to charge!
IR compatibility & signal quality
The Harmony 'database' is a collection of learned signals. Learned signals are never 100% correct, but in most cases it will work. If not, you can adjust the signal (just as with old taperecorders you could increase / decrease the tape speed untill the output was more or less correct). If your lucky, another user has already done this for your devices, otherwise you can spent a couple of hours to make it work. Harmony claims to have more than 175,000 models included in their 'database', however most models are incorrect entries of users.
If your unlucky, you have a device that is using an IR protocol with a very low, very high frequency or even without modulation. In that case the Harmony will not work.
The Harmony 525 will work for (most) devices that use IR modulation between 30 KHz and 70 KHz.
It will not work with Low frequencies, e.g. the Blaupunkt / Siemens IR protocols that use frequencies between 16-25 KHz.
It will not work with the Pace cable boxes that use IRDA.
It will not work with 200/400 KHz protocol (used by e.g. Thomson and Telefunken)
It will not work @ 455KHz (B&O, some Kenwood & Sony Receivers)
(Please note that other manufacturers can also use these protocols for their equipment!)
Now the good news is that Harmony also offers a 6xx and 7xx series that will work with the Pace cable boxes and a 8xx series that will work with most (but not all)High Frequency protocols.
But the best news is that the £20 OFA 6 does offers an incredible IR range from 10-1020 KHz, it has no problem with any of the above mentioned protocols and can even control Sony VisionTouch amplifiers what is still impossible with the Harmony 1000 that cost you a few hunderd £.
Why: because OFA is using the UEI database for IR protocols. It generates the IR signals by using protocol information instead of sending out a good (or bad) copy of a learned signal. And the OFA 6 has a wireless modem, if you have a device that needs new protocol data, you can phone the helpline, tell them which device you want to control and the OFA will be updated by phone. The update takes less than a minute! It is also possible to update the remote by internet, but I have to say that I don't like the OFA website, I prefer updating by phone.
Even better: if you learn a function, the OFA decodes the learned signal and use its internal protocol data for error correction, unlike the Harmony you don't have to mess with timings and delays to correct the learned signal, it recognise the data and use the protocol information to generate the correct signal.
There is here a B&O shop around the corner, Bang & Olufsen remotes are difficult to learn because of their wavelenght and frequency modulation, I know the shop owner and because he wanted to sell universal remotes that can control B&O, we did a couple of tests. The Harmony's can not learn the B&O signals, the OFA 6 learn and control the B&O's with ease.
Is the Harmony that bad? No it isn't, it is just that the OFA 6 is so much better. My brother bought a Meridian CD player & Amp and because the shop did not had the Meridian system remote available, he received a Philips Pronto instead. But because of its ergonomic shape, he prefers his OFA 6.
(but a Philips Pronto or the Harmony 1000 are better "show off" remotes)