Recharge is king on Regens, followed by defense. You don't build for hit points because recharge will give you perma Dull Pain, and the accolades and a couple tiny bonuses will cap your hit points. You don't build for regeneration because you're already swimming in it.
Beyond the Luck of the Gamblers, Doctored Wounds is a very nice set for recharge, and you may want to look at Red Fortune as well. You should have Tough, and if you go for defensive bonuses, Weave. Steadfast Protection unique. Kismet unique.
Buzzsaw has been out since the buffs to the set and particularly to Siphon Life. Siphon Life chains are in. It's not the top chain, but at a moderate level of recharge, you'll probably want Midnight Grasp (6.6 seconds, +128% recharge) -> Smite (3.16 +90%) -> Shadow Punch (+0%) -> Siphon Life (6.73 +49%) -> Smite -> Shadow Punch.
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I'm fully in love with Siphon Life as an attack.
it had been in my build the whole time, but only got used as an emergency heal and was barely slotted. Once I was informed to treat it as an attack however, wow what a change! It's currently slotted with 3 damage IO's and 2 Heal SO's.
So recharge and defense? Interesting, I hadn't thought about defense on him, I can add tough and weave in no sweat though! Makes sense about not slotting for +Regen now that you mention it.
Maestro Mavius - Infinity
Capt. Biohazrd - PCSAR
Talsor Tech - Talsorian Guard
Keep Calm & Chive On!
I'm a huge fan of Touch of Fear, but let me mention that I don't think an IO'd DM/Regen needs it except for a few edge cases. The most common edge case where I would have used it is something like a Sapper, or other annoying single mob that I want to (mostly) disable to remove annoying debuffs Personally, I have dealt with most of those edge cases using epic pool single-target mezzes, which accept more helpful sets, in general, than ToF can accept. If there's more than one annoying mob, I can usually afford to mez one and just kill the other, and if I really don't want them to land their debuff on me, I can usually avoid it with well-timed MoG.
A power you may not have considered is Shadow Meld from the villain Soul Mastery Patron Pool. At high levels of recharge it comes back very quickly, and at moderate levels of defense it is essentially a mini-MoG. You have to go villain to pick it up, but you keep access to it even if you come back to hero side. My DM/Regen is my main badge collector anyhow, so I used the excuse to get a ton of villain-only badges en-route to the power. 
Blue
American Steele: 50 BS/Inv
Nightfall: 50 DDD
Sable Slayer: 50 DM/Rgn
Fortune's Shadow: 50 Dark/Psi
WinterStrike: 47 Ice/Dev
Quantum Well: 43 Inv/EM
Twilit Destiny: 43 MA/DA
Red
Shadowslip: 50 DDC
Final Rest: 50 MA/Rgn
Abyssal Frost: 50 Ice/Dark
Golden Ember: 50 SM/FA
The second character I ever made was my DM/Regen listed in my sig.
After being shelved for quite some time I recently decided to make the final push to 50 with him.
He's a ton of fun atm, picking off Fake Nem's in PI while gathering tips. I think he'll end up being my A-Merit farmer and that's what brings me here.
I mainly solo and play casually most of the time. So I haven't bothered with IO sets much at all. But now that A-Merits can be used to get me the good stuff and I'll be respeccing for fitness soon regardless, I'd like to buff this guy up a bit for the final 5 levels.
Problem is I'm not exactly sure which way to go with that.
I'd considered a buzzsaw build but recently heard that they were no longer king. I'm satisfied with my damage output and would really just like to focus on making myself a bit tougher.
To that end, should I focus on +regen or +HP? I know I'd like more recharge as well, is the +7.5 LOTG the only way to get that?
I'm at work so I can't post a mid's atm. Suffice it to say I'm pretty much wide open on suggestions, only power I really can't see dropping would be Touch of Fear. I currently have every power from Regen (including revive because it gets used) and every power from DM except Confront.
He uses SJ for travel and has Hasten as well but no fitness pool... yet.
Focused Accuracy and Physical perfection represent his anc.
Thanks in advance!
Maestro Mavius - Infinity
Capt. Biohazrd - PCSAR
Talsor Tech - Talsorian Guard
Keep Calm & Chive On!