I have used both, the boiler buddy is less handy for future maintenance and probably impossible for customers to remove for themselves, because you fit it with pump valves. How many customers do you know that could change their own pump? Same sort of job.
I don't imagine there is much difference in viability.
I spent 8 hours day before yesterday with customers help powerflushing each rad outside using chemical for each. Then half of the installation day powerflushing again each rad for 5 mins using chemical via pipework to make sure pipework is flushed also.
Since customer is super nervous (long story old gas boiler wrecked with sludge has cost him fortune for repairs but nobody suggested a powerflush until Vokera man told him the problem) I tried to get a magnaclean but even though I have them on order with a few local merchants Scarborough is completely out of them. Customer got the Fernox one from Malton.
So new boiler is off to a good chance with beautifully cleansed system and boiler bud. As of late last night boiler bud hadn't trapped anything...
Rads are well hot, customer well pleased, excepting fact that new boiler pressure guage not registering and has leak from condense syphon trap (not our connection, another superfluous one which isn't required). Just my luck, never known a pressure guage to fail from new, but most nervous customer in Scarborough, and rightly so, and I get two commissioning fualts.
Good news is the manufacturer is coming today (same day and on a Saturday).
I'd have fixed the condense trap myself but since they have to come out for the pressure guage let them fiddle with it, serve them right for stuffing it into a tight corner!