EDIT: I guess my point is p2pool isn't for everyone. True supporters of the p2pool concept acknowledge that. The rest treat p2pool as a religion, as from their perspective, anyone who has a problem must not have their settings right or not understand the system.
There are people with a setup that can't work well with p2pool whatever they try (ASICMiner blades, clogged or unreliable Internet connectivity for example) but there are people who don't understand how to tune a p2pool setup to work well on their environment too.
Given that p2pool can be configured to use less than 20KB/s and bitcoind tuned to use even less, people with DSL should all be able to use p2pool. The only ways someone can't use p2pool on a link that provides at least 512kbps in both directions I can think of are:
- not knowing how to configure p2pool and bitcoind for low bandwidth,
- not knowing how or being able to use QoS to give priority to p2pool and bitcoind,
- needing the bandwidth for something else,
- unreliable connectivity
On a related subject variance importance is often blown out of proportions and people willingly choose pools that pay between 3 and 5% less monthly because p2pool pays less nearly one day out of two. This behavior is not limited to pool choice: many forfeit long term gains for short term gains in most domains.