You should be pretty good to go. Having said that, speaker are mechanical devices and many believe that speaker surrounds and spiders have a 'break-in' period, but most well built speakers stay within their specifications from the time you purchased them (some have very stiff surrounds and spiders and even the manufacture recommends a break-in period). It really doesn't take long to re-run Audyssey if you feel like you need to.
Now, if you make any major changes to your room: move furniture, add or remove furniture, add or remove other furnishings (such as lamps), change art pieces that can change reflective properties, etc., then re-running Audyssey is probably a good choice. I'm one of those that do re-run Audyssey when there are changes to a room (that the speakers are in of course), even if fairly minor like adding/changing out a different guitar that is hanging in the room - they are different reflective surfaces. Even things such as Christmas - the living room really changes for 1 month. Do I re-run, yes I do. But, I do a network save on those AVR's that have that function (yours has that) so I can easily re-load the settings after we change it back. If you AVR is attached to your network, I highly recommend doing a network save to you computer. It can save a lot of headaches on re-naming inputs, assigning inputs, and re-running Audyssey if there were to be a glitch and you had to re-set the AVR's microprocessor (which would set it back to default settings). Sometimes things like power surges can cause an AVR to glitch (some have actually had all their settings, including calibration, wiped out with a power surge.
So, bottom line - it's up to you. I'm pretty anal about re-running a calibration if there are changes. Many are happy leaving it as is (especially if in a multi-use room where things will change on a daily basis, then there is no point).
It looks like they found a way to make your speaker stands cheaper as it's much easier just to weld than add screws and machine the threads. Like you stated, they are made of heavy steal so if you feel it's heavy enough you can leave it be. The spikes are great, once you adjust them, the stand becomes firmly mounted to the floor.
Enjoy your new system!!!