On salt water / vacation boat dives I always use rental gear. Not that much $$ to use and I get experience with ALL sorts of equipment. And if some emergency comes up (which it never has) more good training experience.
About the worse things I've found is depth gauges are off, regs are hard to breath or free flow some and pressure gauges are in bar and could not figure them out.
On the fresh water springs I use my own gear. I got 5 regs (3 modern, 2 older vinatge)
Never have had trouble with my own regs even with no servicing after 6 years for some. But I use triple redundancy - 1 pony reg, 1 main reg, and 1 back up reg. And if a reg does have trouble it just blow bubbles and wastes some air. It is not like it shuts down 100% (unless it gets frozen)
I was able to get my dive shop to replace the low pressure seat for about $12 ea in 2 old regs from ebay. As far as buying your own repair parts? Very hard to do in my experience.
I think the yearly reg repair work is for the shops to stay in biz. But on some hard tech or abusive day in and day out dives, seasonal teardowns are in order.
I am always amazed though at the people on the dive boats that use rental gear and only breath once or twice out of the reg to test it. I breath for about 15 seconds before I take the dive...rental gear or my own gear!
Computers? Don't use them. Do not dive near limits so would be a waste for me. Dive once a day, maybe twice sometimes. Nothing deep, average 40 to 60 feet, sometimes 70 to 80 feet.
