I am running Ohm Force Frohmage in Pro Tools LE 7.4 and I am running Pro Tools LE on a Mac Book Pro laptop that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I run Pro Tools LE with a Digi 002R audio interface. With this configuration, the plug-in has always been stable as I haven't ever had a problem with it since installing it. I am able to run a few of these at a time on different tracks, but never go too crazy with it so I can't speak to how well it would run if you had a lot of these running at once.
I've been using the Ohm Force Frohmage resonator filter for about six months. Since it is a free piece of software, I really have no complaints about this plug-in. It is great at what is does and is capable of getting pretty in depth in terms of filter parameters. It has a good sound quality and I have found it useful in a number of different situations. I don't know of any plug-ins I would compare it to, but this plug-in opened the door for me to try some of the other Ohm Force plug-ins and I have been throughly impressed by them. Beyond this free plug-in, they make some great plug-ins that are extremely cheap. As far as Frohmage goes, I recommend it to anyone who has a digital audio workspace as it is useful and free!