I believe Bare had a licensing deal to use the name Celliant, and that deal ended. So, the new all black (Titan) suit says it has "Ultrawarmth", instead of the blue and red suit's labeling as "Celliant". My Bare contact assures me it's exactly the same, just not using the trademarked name any more.
I have the 3 and 5mm versions in the newer black color. They are very nice (and warm) suits.
I have used my Reactive 5mm (with 7mm hood, 5mm boots, and 3mm gloves) in water down to 51 degrees for 50 minutes, with a max depth of 59', followed by a second dive in the same water for 71 minutes, with a max depth of 43'. I was cold, but not freezing. I did not get numb anywhere. I would say I am pretty cold-tolerant, though. I could probably dive a 7mm Reactive in water that is high 40s and be reasonably comfortable for a couple of normal recreational dives. However, while I could do it, I would not.
I reckon it's personal preference, but I like a 5mm wetsuit just fine and hate a 7mm. I have 2 7mm suits. I have worn them each less than a handful of times. Now that I have 2 good-fitting drysuits, I can't see myself ever wearing a 7mm again. To me, they cross the line into just too danged thick.
If I *were* really set on diving in water in the upper 40s, in not-a-drysuit, I would very likely get a semi-dry suit like the Hollis NeoTek. I've seen a lot of positive reviews of that suit and I don't remember ever seeing anyone say anything bad about it.
All that said, I agree with
@drk5036. A Seaskin drysuit is very inexpensive and top quality - and made to measure. A Seaskin neoprene drysuit is very much like a wetsuit - only a little more loose and a lot warmer.
I have Seaskin suits in trilam (aka membrane) and compressed neoprene. They are both really great suits. For water in the 40s (or lower), I would use the trilam, since it has rings for dry gloves. In those water temps, it's my hands that end up making the difference for me on comfort. My hands would be really cold in 40-something water in wet gloves. You can get dry glove rings on a neoprene suit, but I did not. I specifically bought my neoprene drysuit to use in water that is warm enough for wet gloves (i.e. 50 and up).
Dry Suits from Seaskin Custom Drysuits home page - Seaskin Custom Diving Suits