Welcome to HW...sorry you have to be here but I'm sure you will find lots of info as well as caring folks here.
In specific answer to your question about experience with LDR brachytherapy, please feel free to copy and paste the link at the bottom of my signature to get a fairly detailed first-person journey of my brachytherapy experience.
Beyond that, if you'll permit, I will make a few other observations about the info you provided:
1. You described your cancer as "very, very early". Honestly, with a Gleason 7 you have intermediate stage cancer. That doesn't mean it's terrible (I was a G7 as well) but - especially with the 4 as predominate - this is intermediate stage cancer.
2. You had a very small sample size with your biopsy. The standard sample size for most urologists is 12. Mine was 16. Insurance may have only covered 7 samples but, with fewer samples, there is less info about your cancer. For example, you say that "the other lobe is clean". That may or may not be true. What is true is that, with only a few samples, the biopsy did not find cancer in the other lobe -- that does not mean it is not there.
3. We have a couple of posters on this site you have used focal therapy -- Ziggy is probably our resident expert. Hopefully he will weigh in. When and if he does he will tell you that this procedure will require a saturation biopsy to better determine the location of the cancer so that it can be properly treated.
4. The placement of the seeds, should you choose brachytherapy, will likely allow radiation to penetrate beyond the wall of the capsule therefore treating any cancer that may have slightly escaped.
5. Frequently with a G7, a RO may recommend brachy + IMRT. But...with only 1 core and 20% brachy alone may be recommended. Personally I would feel better doing brachy with 1/12 or 1/16 rather than 1/7.
Hope this is helpful. Feel free to ask any more questions and please keep us up to date.
Age 62 (65 now), G 3 + 4 = 7, T1C, PSA 4.2, 2/16 cancerous, 27cc. Brachytherapy 12/9/08. 73 Iodine-125 seeds. Procedure went great, only minor discomfort. Everything continues to function normally as of 12/2/11. PSA: 6 mo: 1.4, 1 yr: 1.0, 2 yr: .8, 3 yr: .5. My docs are "delighted"! My journey: