I would never pay for the service plan and never have.
Ignoring the fact you can add it when needed, over a two year commitment it would cost $168 to protect $500-$1000 of equipment at retail prices. Would you pay for a 2 year warranty on a TV at those kind of expense ratios? Unless you purchase the receivers, you are never looking at that total retail cost. Even if over that two years you need to ship two receivers and have a service call, you would only be looking at a cost of around $150.00, basically break even with the cost of the plan.
Add in the fact you can add the plan when needed, and it makes no sense to pay for it continuously.
Anecdotally over the years, I've had a couple of replacement receivers shipped, several upgrades (including SD to HD and VIP to Hopper), plus a "mover" visit and never paid a penny for shipping or a tech visit. Luckily I've never had to have a purely service visit.