Hi Gerry,
What has been holding me back is that I'm a bit skeptical if your amps would sound better than my 45 amp. However, the one major advantage your amps have over mine would be the additional power output (my speaker sensitivity is about 96dB and does not use a xover).
The Signature 30 might sound better to you overall, or you might like certain things better with the Sig 30 vs. your 45 amp, and vice versa.
I am fairly confident that you'll
at least find the Sig 30s to be more dynamic, have better bass articulation and control, and a blacker background (no hum). You'll also be able to play cleaner at louder volumes.
That alone has me curious enough to place an order. However, before I do so, I would like to know if anyone has ever returned a Signature amp? If yes, what were the reason(s) stated.
Returns? Never!

Just kidding... but I am very pleased to have such a very low return percentage on the Sig 30s and Sig 70s. Some of the reasons for return:
-- Upgrading to the Sig 70s (returning a Sig 30)
-- Hard-core, die-hard tube fanatics realize that although the Sigs have tube-like qualities (and even do certain things they like better than a tube amp), the Sigs are NOT tube amps.
The other reasons are pretty common to
any amplifier manufacturer (who is confident enough in their products to offer a return policy):
-- Not the best overall synergy with the rest of their system (not enough detail/top-end, too much detail, too much bottom-end, not enough bottom-end, etc. etc.)
-- Not enough power for the speakers used and the size of the room
If you seach through the RWA forum archieves since the Sig 30 came out in May/June 2006 (and the Sig 70s last Fall) you'll find LOTS of customer feedback. You'll also find a few online reviews on my website. However, no matter what you read and how much reading you do, you won't know what they sound like
in your system and
to your ears until you try them for yourself.
Hope this helps,
Vinnie