I think your problem is with the chassis, not the rig. I believe your Sea Breeze is on the Ford V-10 Chassis. If so, it is not as powerful as the Workhorse chassis w/the 8.1 ltr Chevy. However, I have a buddy with an '03 Sea Breeze 8341 on the F-53 and he has very little trouble climbing hills. No more than any other Class A would have. Diesels definitely are superior in climbing hills to a gas rig. Ride is steadier as well.
As to the Sea Breeze itself, it was made by National Rv and is a nice coach. National has a fine reputation for quality motor coaches. I had a 1998 Dolphin, which was great and just upgraded to a 2005 Sea Breeze LX on the W-24 chassis.
For three people full-timing, I might suggest a slightly larger coach, say 35 to 38 foot. Lots of good RV's for sale out there. Take you time, and look over as many as you can to find the one that best fits your needs.
If you like the Sea Breeze, it is in good shape and the price is right, go for it! you can add the Banks Powerpack w/Trans command for added power. I added that to my '98 Dolphin and got a big boost in power! Climbs hills like a champ. If you plan to keep the rig for 5 years, or more, I think the $3400 investment in the Banks is well worth it.
Good luck, and keep us posted!