Like Kona I've used both North Hill and Sunridge and have mixed feelings about both.
The CSRs I've dealt with at Sunridge come across as 'know-it-alls' which can be pretty frustrating at times. There was this one guy trying to explain to me that a TSB for a PCM reflash on a US Mazda5 does not apply to the Canadian Mazda5 and I would have to pay $$ for this to be done....while I'm still under warranty, fall within the VIN number range and all the NA Mazda5's are buily at the same factory. He is an idiot.
The folks at North Hill's service and parts department cannot be beat for customer service and attitude.....however they can let small things slip through the cracks so you need to be constantly following up with them.
After all is said and done, I would go to NHM anyday purely based on their superior customer service.
NB. The entry to NHM's service bays is really steep. If your vehicle is lowered you MUST ask them to be careful getting in/out of the bay. They destroyed the front lip on my Mazda5 the last time I was there......I'm still trying to source a replacement which they will be paying for (of course).
Anthony