Using a Rune of Solitude - DM or no DM? (in General)

Well the title says it all. I'm reasonably new, and I just don't know if there is one that is strictly better, or maybe better in most cases.
Here's what *I* think is going on.

1. I must use a RoS, on principle alone ;p

2. Almost everyone has an ED worth dispelling, and it's plainly obvious that using a DM 1/4 my RoS would be advantageous.

3. (don't quote me on this) maybe 1/4~1/2 of the top 50ish players use DM of various sizes.

4. It is plainly obvious why NOT using DM against those players would be of advantage - my team thrives on ED and cannot win when it is whittled down.

5. So then I have a choice - run DM and gain an advantage versus non-DM enemies (using DM at 1/4 of my RoS), or do not run DM and simply use RoS as DM protection and ED buffer.

6. In terms of XP, is keeping a DM 1/4 the size of my RoS worth more than say, AS?

Any input would be appreciated, and please look at my strat before making your valuable comments! Remember, my RoS is on the GA minion ;p
Oh, and comments which will not be appreciated are "your strat would work better with x and x tattoo". Read number 1 x-D

You do have room for DM. And the RoS. Not really any reason not to use it. Apart from XP spread.

But, not to pull apart your strat as it stands but I'd consider swapping the smaller of your AS's completely to DM, and putting the RoS on the AS enchanter to boost AS rather than GA. Your mage will last longer, thus do more damage with more HP, so you probably won't have to rely on GA as much.

If you're going to have DM it's probably not worth having small. If you can't nuke their ED's then IMO it's not worth using.