I can't speak to any of those gyms, but I've heard really good things about the Muy Tai classes at Valley Forge Training Center. It has a Norristown mailing address, but I'd call it Worcester. It looks like according to their website, Chris Beltrante has more info about those classes at his website Beltrante Fighting Fit

I walk my dogs on the SRT almost every weekend, they just paved the section by me at the beginning of this year and it's been great.