Thanks to all who responded. As suspected, it was the multiswitch, the Pico-Macom TSMS-4/8. The tech replaced it and everything seems to be working fine with signal strength numbers now in the mid to high 90's on any channel.
But just a few comments on the service call 'experience.' I realise Shaw uses 3rd party local service orgs to handle house calls but ultimately they are Shaw's representative in your home and this visit left a lot to be desired.
1) If the entire call was predicated on the customer's belief that their multiswitch was suspect, wouldn't you think the tech would have a replacement in his vehicle? Turns out he didn't have the Pico-Macom TSMS-4/8 on hand, the very one he confirmed SD still use exclusively for residential installs, so he ended up substituting it with a smaller non-boxed non-powered one he claimed they only use in commercial installations. No make or model markings whatsoever although 'DirectTV' is referenced on the label. At least I no longer have the secondary heating source in our utility room anymore that the Pico-Macom TSMS-4/8 was.
2) The rep seemed very rushed. This even included him at one point dropping the new switch from about 5 ft. onto the concrete floor. When I mentioned that must be and indication of how busy they must be, he admitted things are very slow at the moment. I can only wonder why I had to wait 5 days to have someone visit. Yes, I know many wait far longer but still. . . . .
3) At no time were any tests done using any sort of scopes or instruments. The only verifications were done using the system status readings on the two 'suspect' PVR630's that Shaw phone support has so often suggested were bad and needed replacement. The irony!
4) Lastly, and somewhat unrelated to the satellite experience is the fact that this rep parked in our driveway. Arguably any professional tech, tradesman or visitor knows not to for various reasons not the least of which is the new oil stain ours now bears as a result.
Oh well. . . . . . . . . .